UNIVERSITY OF SASKATCHEWAN

This volume is the property of the Unlversl ty .. Saskatchewan, and the literary rights of the author and of the University must be respected. F' :he reader ob­tains any assistance from this volume, he must give proper credit in his own work.

This Thesis by . . .G~O!g~ ~el1 ~ol~n?s~y. . • • " • • • "r: • « • • • " •

has been used by the following persons, whose signatures attest their acceptance of the above restri cti ons .

Name and Address Date

THE LENS AS AN INDEX OF AGE IN THE

PRONGHORN ANTELOPE (ANTILOCAPRA AMERiCANA ORO.)

.A

Thesis

Submitted to

the Faculty of Graduate Studies

in Partial Fulfilment of

the Requirements for

the 0 egree of

Jv\aster of Arts

in the

Department of Biology

University of Saskatchewan

by

GEORGE BEN KOLENOSKY

Saskatoon, Saskatchewan

July I' 1961

The University of Saskatchewan claims copyright in con junction wi.th the author. Use shall not be made of the material contained herein without proper acknowl edgement•

OCT 192514 6 1961

TABLE OF CONTENTS

Page

INTRODUCTION ••••••••••••••• _••••••_•• • •• • •• • • • • •• •• • • • e,. •• • t

ACKNOWLEDGEMENTS ••••••••••••••••••••••••••••••••••••••• 3

ANATOMY AND DEVELOPMENT OF THE MAMMALIAN LENS 4­

METHODS AND MATERIALS................................... 8

RESULTS

Measurement of the Cornea 11oooooooooooooooooooooooooooooooooooooooo.oooooooooooooooooo

Lens Measurements

Preparation of the Lens 14­oooooooooooooooooooooooooooooooooooooooooooooooooooooooo

Wet Weight of Lens oooooooooooooooooooooooooooooooooooo .. oooooooooo .. oooo .. oooooo 14

Lens Volume oooooooooooooo.oo .. oooo .. oooooo .. oooo .... oooooooooooooooo .. oooooooooooooo 15

SpeeIfie Gravity of Lens oooooooooooo .. oooooooooooooooo .. oo .. oo .. oooo oooooo 18

Dry Weight of Lens 18oooo •• oo oo.oooooooooo.oooooo oo..

DISCUSSION .... ., . 26

SUMMARY •••••••••••-•••••• • • • • • • • • •• • • •• •• • • • • • • • • • • • • • • '•••• 28

LITERATURE CITED .......... ............................... '... 29

APPEND.IX I •••••••••••••••••••••••••••••••••••••••••••••••••• (i)

APPENDIX II ' ' . (vii)

List of Tables

Page

I. Dental Characters Used to Establish Antelope Age Classes..... 9

u. Arrangement of Specimens into Age Classes on the Basis of Dental Characters ••• • • • • ••••• ••• • • • • • • • • • • • • • • • • • • • • • 10

IIL, Relationsh ip of Cornea Size to Age •••••••••••••••••••••••• 13

IV. Mean Values and Ranges for Wet Weights" Volume and Specific Gravity of Antelope Lenses. • • • • • •• • • • • • • • • •• • • • • • 16

V. Dry Weight Data of Antelope Lenses......... • • • • • • • • • • • • • • 19

VI. Comparison of Wet Weights, Volume and Dry Weights of the Antelope Lens •••••••••••••••••••••••••••••••••••• 21

VII. Chart to be used to Estimate Ages of Antelope, when Dry Weights of Lenses are Known ••••••••••••••••••••••••• 25

LIst of FIgures

Page

1. Sketch of horIzontal section of mammcdian eye, showing position of lens and ad lacent structures ••••••••••••••••••••••••••••••• 5

2. Diagram of the lens, showing thickness of capsule in various areas.. 5

3. Meridional section of the equatorial region of the lens, showing growth of new fibers at the equator ••••••••••••••••••••••••••• 6

4. Growth of lens in man •••••••••••••••••••••••••••••••••••••• 7

5. Sketch of a lateral view of the lower jaw of a pronghomantelope, illustrating position of various teeth referred to in text ••••.••••• 7

6. Sketch of a ventro-Iateral view of an antelope eye after removal from the skull, illustrating cornea measurements taken.... •• • • • • 12

7. Growth-rate curve of the cornea of the antelope eye.... •• ••• •• 12

8. Growth-rate curve of the lens ofthe antelope eye. •• ••••• • •• • • 20

9. Enlarged portion of the latter part of the growth-rate curve of the lens ••••••••••••••••••••••••••••••••••••••••••••••• 20

INTRODUCTION

The rate of growth and subsequent density variations in a natural population

depend upon natality rate, mortality rate and age structure, but in order to determine

each of these rates one must first know the age of the individuals from which data

are taken. The population characteristics of big game species are poorly known,

partly due to the fact that adequate age criteria are stiU not available.

The criteria used to establish the age of an animal must satisfy several

requirements, especIally if these criteria are to be uniformly applicable to members

of different populations living In different habitats. If an age character is a function

of growth and development, it should not be affected by such variables as temperature

and nutrition. If It is subject to wear I the rate of wear should be uniform between

different individuals and populations, regardless of habitat. Finally I if the animal

Is relatively long-lived, as is the case with most, if not all, big game species, the

character must change at a predictable rate throughout the IHe of the individual.

Age criteria which satisfy all of the above requirements are rare among

animals. Many attempts have been made to discover annular growth rings, like

those in trees, in animal structures, but the only known examples are the growth

rings in fish scales, those in the canine teeth of seals and their relatives (Scheffer,

1950) and the growth rings on the horns of bighorn sheep (Ovis canadensis) and

their relatives (Murie, 1944). Zones of annual growth have been reported in incisor

teeth of moose (Alces alces) by Sergeant and PlmIott (1959) but this character is only

dIscernible for the first few years of age and remains to be fully evaluated in any

event.

A structure In mammals which grows continually throughout IHel but which

has only recently been studied with respect to its applicability as an indicator of age

is the lens of the eye. Lord (1959[ 1961) found that the lens served as a reHableage

indicator in cottontail rabbits (Sylvilagus floridanus) and gray fox (Urocyon cinereo­

argenteus floridanus).

The purpose of the present study is to describe the rate of growth of the

2

lens of the eye in pronghorn antelope (Antilocapra americana) and to establish,

within the limitations of the data available, an age index for this species based

on lens growth and size.

3

ACKNOWLEDGEMENTS

This study was done under the supervision of Dr. R.S. Miller, to whom

I would like to express my sincere appreciation. I am also indebted to Dr. P.L.

Wright, Montana State University, who aged a sample of [cws and advised on the

use of dental characters as age criteria. To those who assisted in the field collections

of antelope specimens, I express my sincere gratitude.

This research was supported by a bursary from the National Research Council

of Canada.

4

ANATOMY AND DEVELOPMENT OF THE MAMMALIAN LENS

The position of the lens and cdjccent structures is shown in Figure 1.

The lens of the mammalian eye is entirely enclosed by the lens capsule, a thin,

transparent membrane lying immediately cdjccent to the lens substance. The

capsule is thicker on the anterior surface of the lens than on the posterior surface

(Adler, 1953), as shown in Figure 2. The varying thickness of the capsule is

believed to be an important factor in lens accommodation.

The lens substance is composed of layers of fibers which form concave

meniscus plates, thinner near the center than at their ends and running from the

equator on one side of the lens to the equator on the other (Figure 3). Wanko and

Gavin (1959) have shown that each lens fiber is an elongcted, prismatlcally-shaped

cell with a hexagonal outline in transverse section. The anterior surface of the lens

is faced with a layer of epithelial cells lyIng immediately beneath the capsule, but

there are no epithelial cells on the posterior surface of the lens.

The mammalian lens is an epithelial structure which, like other epithelial

derivatives such as hair and fingernails, continues to grow throughout the IHe of the

individual. As additional lens fibers are produced by the epithelial cells on .the

anterior surface, the fibers already present are compressed toward the center of the

lens. Due to the density and avascular nature of the lens fibers, the fibers at the

center of the lens tend to lose their cell membranes, the cytoplasm loses water, and

the fibers become dense and rigid, forming a dense core at the center of the lens

(Lansing, 1952). In man, after the age of 30 years/this core may become so large

and dense that it interferes with the deformation of the lens during accommodation.

As the fibers are compressed toward the center of the lens they become

smaller, but Increase in relative density so that the total weight of each fIber remains

approximately the some. ThusI new fibers may be formed continually without unduly

increasing the sIze of the lens, while the weIght of the lens increases as the new fibers

are added.

The rate of increase in weight of the lens in man is very rapld during the

early years of life, but much slower during later years (Scammon and Hesdorffer, 1937).

5 ___~-----CORNEA

CONJUNCTIVA

'~--SCLERA

fiigure 1. Sketch of horizontal section of mammolian eye, showing position of lens and cdjccent structures.

ANT E RIO RCA PS UL E

-. EQUATOR

IPOSTERIOR POLE

Eigure 2. Diagram of the lens, showing thickness of capsule in various areas. (Ad Ien Physiology of the Eye, St. Louis, 1953, The C.V. Mosby Company.)

6

ANTERIOR/

CAPSULE----------~

EPITHELI UM---+--t"­

EQUATOR ---I

NUCLEI OF

LENS FIBERS

Figure 3. Meridional section of the equatorial region of the lens showing growth of new fibers at the equator. (Adler: Physiology of the Eye, St __ Louis, 1953, The C. V. Mosby Company.)

7

400

350

300

250 (/)

::E <[ a:: ~ 200 ...J ...J

~

~ 150

/ ./

.----~--L.----l----'

~

/ I­:t: C)

W ~

100

(/)

z ~ 50

YEARS: 10 20 30 40 50 60 70 80 90

Eigure 4. Growth of lens in man. (Bellows: Cataract and Anomalies of the Lens, St. Louis, 1944, The C. v. Mosby Company).

F,igure 5. Sketch of a lateral view of the lower law of a pronghorn antelope, illustrating position of various teeth referred to in text.

8

The wet weight increases by about fifty percent in the first six months after birth

and at the age of one year is approximately twice the weIght at birth. At thirty­

flve yecrs of age the weIght of the lens is approxImately three times the weight at

birth and at seventy-five is cpproxlmctely four tImes the weIght at birth (Figure 4).

Scammon and Hesdorffer (1937) derived the foil owing formula in which

L, W. is the lens weIght In millIgrams and A is the age in years:

l.W. =137.115 mg. + 1.429 A

METHODS AND NlATERIALS

A total of 92 adult antelope and 13 fetuses were collected throughout the

ProvInce of Saskatchewan from October I 1960 to May I 1961. The largest sample

(69 specimens) was obtained during the hunting season in November J 1960 at check

stations located at Maple Creek, Sbcunevon, Val Marie, leader and Mankota.

The most reHableaging technique presently available for blg""'9ame species

is based on the dentition of the lower law.An estimated age was assigned to each

specimen on the basis of tooth eruption, development and wear J as outlined by Dow

(1952, unpublished). These criteria are shown in Table 1 and the position ofthe

teeth of the lower jaw are illustrated in Figure 5. Radiograms of the lower iaws

were used to supplement the classifications that were made on the basis of external

dentition. The number of specimens in each age class Is shown in Table II. The

ages shown are based on an assumed birth da te of June l ,

A representative sample of 13 lower laws was sent to Dr. P.l. Wright at

Montana State UnIversity for verification of ages assigned by the author.

The methods used to prepare and measure the lens and assocIated structures

are described In appropriate sections of the results.

9

TABLE I

DENTAL CHARACTERS USED TO ESTABLISH ANTELOPE AGE CLASSES (AFTER DOW, 1952)

Age Dental criteria

Incisors and canines Cheekteeth,

3 to 5 months

15 to 17 months

27 to 29 months

39 to 41 months

4 1/2 years

5 1/2 years

6 1/2 years

7 1/2 years

8 1/2 years

9 1/2 years

All temporary

One permanent incisor

Usually 2 permanent incisors

Replacement not consistent

Replacement not consislent

Replacement not consistent

All permanent

All permanent

All permanent

All permanent

3 temporary premolars, first molar present

3 temporary premolars, 3 molars present

Permanent premolars unworn, all molars present and showiog wear

11 or 12 infundibula

9 or 10 infundibula

7 or 8 infundibula

5 or 6 infundibula

3 or4 infundibula

1 or 2 infundibula

No infundibula

10

TABLE II

ARRANGEMENT OF SPECIMENS INTO AGE CLASSES ON THE BASIS OF DENTAL CHARACTERS

Establ ished Age Class Number In Each Class in Months

5 21

17 24

29 15

41 11

53 5

65 2

77 5

89 5

101 3

113+ 1

Total 92

11

RESULTS

Measurement of the Cornea

The greatest length and width of the cornea was measured (Figure 6) r

using a paIr of sharp poInted feeler caJipers to determine the distance/ which

was then transferred to vernier cal ipers for readi n9. Each eye was measured

separately and the average of the two eyes used as the recorded measurement

for each animal. The corneas of fetuses four months or older were measured/ but

the eyes of younger fetuses are not sufficiently developed to allow accurate

measurement.

The relationship between size of the cornea and age Is shown in Table

HI and Figure 7. There Is a rapid increase in cornea size in young cnlmcls, but

no measureable increase after about two years. The ratio of length to width was

more variable than either of the two recorded measurements. These data reflect

the fact that the bony socket enclos.1ng the eye cannot grow indefinitely and reaches

its maximum size in about two years. Similar results were obtained by Scammon and

Hesdorffer (1937) for the human eye. After a certain age the eye as a whole ceases

to grow, although growth of the lens continues. Thus, during the early years, the

lens is a decreasing component of the eyeball, but becomes an increasingly larger

component as age progresses.

Because of the variabiUty within age groups and the small amount of increase

in size of the cornea after two years of age, this character is not a satisfactory indicator

of age.

12

DORSAL

ANTERIOR POSTERIOR

f;=igure 6. Sketch of a ventro..lateral view of em antelope eye after removal from the skull, illustrating cornea measurements taken.

~LENGTH40

0----8 WIDTH

35

30

.0-----0--- -J;)-- -..0. - ---~----o

~

ILl N iii ca: ILl

25

__

Z C)II:: 0 u

5

~igure 7. Growth-rate curve of the cornec of the antelope eye.

TABLE iuRELATIONSHIP OF CORNEA SIZE TO AGE

Number InEach Group

(4)

(2)

(4)

(16)

(19)

(14)

(8)

(4)

(2)

(2)

EstImated Age of Antelope (months)

.4 (i nter-uterine)

6 (Inrer-u ted ne)

6 1/2 (lnter-uterlne)

5

17

29

41

53

65

77

Mean Cornea LengthIn Millimeters

10.38

17.47

18.70

23.66

25.79

26.52

27.30

27.55

28.00

28.50

Mean Cornea Width in Mill imeters

8.79

12.60

13.76

17.68

19.83

20.07

20.56

20.90

20.65

20.55

Mean Ratio of Length Width

1.181

1.386

1.359

1.338

1.300

1.321

1.328

1.318

1.356

1.387

w­

14

LENS MEASUREMENTS

Preparatlon of the Lens

Various methods of lens preparation were tried at the beginning of this studyI

in order to establish an accurate technique which can be used under the various

field conditions that are encountered in collections of big-game material. It was

found that the lens is subject to distortion and damage if not carefully preserved, but

is quite durable if treated properly. The following technique is recommended.

Each eye should be Injected in situ with 10 percent formalin as soon after

the death of the animal as possible. A plastic syringe and a number 18-20 needle

was found to be satisfactory. The point of Injection should be near the edge of the

eye to avoid striking the lens. Enough formalin should be Injected to make the eye

turgid.

After In[ectlon the entire eye can be removed and placed in 10 percent

formalin. If only the lens is to be removed, a period of at least twenty minutes is

required before the lens becomes sufficiently fixed to be removed without distortion

or damage. Once the lens has been fixed it is quite durable and maintains its shape

with frequent handling, but should be returned to the formal in solution after each

examination.

During winter months the formalin solution was subJect to freezIng l which

resulted in radial splitting of the lenses. Under these conditions a mixture of 30

percent alcohol and 10 percent formalin was used. This solution caused a slight

but relatively insignificant decrease in the density of the lens.

Wet Weight

After fixing, the lens was removed from the eye, rolled on a paper towel

a few times to remove excess surface moisture I and then weighed to the nearest

hundredth of a mill igram. The wet lens loses moisture when exposed to air and

therefore must be weighed immediately. The wet weights of the lenses are shown

in Table IV. A considerable amount of variability1 both within the various age

15

classes and also between the right and left lens was found in the wet weights. The

standard deviations for wet weights within age classes ranged from 72.3 mg. to

128.4 mg. (Table VI). The mean difference between the right and left lens was

31.53 mg. or a mean difference of 2.20 percent of the total mean weight.

Volume

To determine the volume, the wet lens was suspended on the end of a needle

and weighed under water. The loss in weight is equal to the volume in cubic milli­

meters. An alternate method is to drop the lens into a water-filled glass cylinder and

measurer by means of a graduated pipette, the amount of water displaced. A small

amount of Sodium Taurocholate added to the water gives a flatter meniscus and hence

a more accurate measurement. Results of the volume determinations are shown in

Table IV. Differences between right and left lenses and within various age classes ore

similar to those for wet weights. The mean difference in volume between the right and

left lens was 31.56 cubic millimeters. The percent difference of the total mean volume

between the right and left lens was 2.40. The standard deviations within the age classes

ranged from 68.6 cubic millimeters to 127.2 cubic millimeters (Table VI).

TABLE IV

MEAN VALUES AND RANGES FOR WET WEIGHTS, VOLUME AND SPECIFIC GRAVITY OF ANTELOPE LENSES

EstimatedAge Number in Mean Wet Mean Mean SpecIfic in Months Each Class WeIght Range Volume Range GravIty Range

3 (inter-uterine) 2 70.73 70. 17 .... 71•30 63.37 62.27 - 64.47 1.1163 1.1059 ... 1.1268

4 (lnrer-oterlne] 5 182.37 153.90 ... 218.32 168.26 140.90 ... 199.05 1.0978 1.0825 - 1. 1173

6 (inter-uterine) 2 43] .48 431.30 .. 431.67 398.73 396.70 ... 400.77 1.0821 1.0771 ... 1.0872

6 1/2 (lnter-uterlne) 4 524.74 511.80 - 595.05 479.33 467.70 - 495.95 1.0946 1.0900 - 1.0990

5 16 1044.73 882.90- )189.25 942.34 792. 10 .. 1081 •85 1. 1088 1.0992 ... 1. 1156

7 1 ]262.17 1262. 17 1150.67 1150.67 1.0970 1.0970

9 2 1281.97 1198.42 - 1365.52 1170.83 1099.02 ... 1242.65 1.0949 1.0904 - 1.0988

10.5 2 1492.15 1458.80 - ]525.50 1365.65 1332.40 ... 1398.90 1.0926 1.0948 ... 1-.0904

17 19 1502.37 1317.70 ... 1667.85 1347.67 1168.20 .. 1497.32 1.1139 1. 1041 - 1•1279

19 2 1618.40 1575.90 .. 1660.90 1465.60 1423.00 - 1508.20 1.1042 1.1042

20 1 1690.70 1690.70 1532.20 1532.20 1.1034 1.1034

21 2 1651.95 1636.20 .. 1667.70 1498.85 1490.60 ... 1507. 10 1.1021 1.0976 - 1.1065

29 14 1666.27 1563.70 .... 1798.02 1513.53 1395.70 .. 1617.72 1•1151 1•1090 - 1. 1208 -

34.5 1 1847.57 1847.57 1675.47 1675.47 1.1027 1.1027

-0-.

--

TABLE IV (continued)

..Estimated Age in Months

Number in Each Class

Mean Wet Weight Range

Mean Volume Range

Mean Specific Gravity R0r'lge

41

45

46

53

65

69

77

89

101

113+

8

2

1

4

2

1

2

3

1

1

1793.06

1833.62

1887.28

1960.35

1997.44

2096.60

2054.40

2017.36

2342.85

2264.87

1650.90 ... 1963.55

1789Q55 - 1877.50

1887.28

1841.85- 2039.25

1992.55 ... 2002.37

2096.60

2018.40 - 2090.40

1874.20- 2122.52

2342.85

2264.87

1621.91

1647.57

1702.. 18

1759.18

1794.08

1916.15

1843.70

1798. 12

2122.05

2023.42

1476•. 60 ]775. 17

1600.75 1694.40

1702. 18

1645.45 - ]820.25

1795.07 - 1850.00

1916.15

1806.80 ... 1880.60

1655•30 - 1899. 17

2122.05

2023.42

1. 1055

1.1129

1.1087

1. 1143

1.1133

1.0941

1. 1142

1.1220

1.1040

1.1193

1•1061 ... 1. 1204

1.1080 - 1•1174

1. 1087

1• 1099 ... ) . ) 193

) .0823 .. 1•1100

1.0941

1. 1115 - 1. 1171

1. 1132 - 1. 1176

1.1040

1. 1193

""'-l

18

SpecIfic Gravity

The specific gravi.ty was found by dividing the wet weight of the lens by

the lens volume. These determinations are also shown in Table IV. These data show

that lens density increases with an increase in agel but the rate of increase is too small

and the variability too great to aUow specific gravity to be used as an accurate index

of age.

Dry Weight

Dry weights were obtained after the lenses had been thoroughly dried at

60° C. for 48 to 72 hours. lenses taken from fetuses required about 24 hours for

complete drying. Once dry the lenses have to be weighed immediately as they are

hygroscopic and gain moisture when exposed to air. The dry weights are shown In

Table V. These gave much less variable results than either wet weights or volume;

both between the right and left lens and also within the various age classes. The

mean difference between the right and left lens was 5.51 mg. The percent difference

of the total mean weight is 1.10 mg. I which is one-half the amount of difference shown

by the wet weights and less than one ...half of the difference shown by the volume. The

standard deviations within the various age classes ranged from 9.2 mg. to 26.7 mg.

This is less than one-fifth of the standard devIations shown by either wet weights or

volume (Table VI).

The growth-curve shown in Figure 8 was based on the dry weight data (Table V).

This curve suggests a division of lens growth into three periods or phases. The first

(which may be termed the logarithmic phase) extends from three months (interuterine)

to five months of age. Lens growth during this phase Is very rapid and shows a straight

lIne relationship between weight and age. The regression of weight on age gave a

value (b) of 34.86 mg. increase per month. The correlation value (r) of .998 is highly

significant. The derived equation is:

Y = 34.86 X - 90.13 mg.

where X =estimated age in months (from conception). The dry weight increased from

15 mg. to approximately 360 mg. during this phase.

19

TABLE V

DRY WEIGHT DATA OF ANTELOPE LENSES

Estimated Age In Months

Mean Weight of Lens (mg.) Range

Number in Each Class

3 (i nter-uterine) 15.61 15.22 - 16.00 2

4 (inter-uterine) 44.78 36.65 - 54.55 5

6 {inter-uterine} 114.97 111.57 118.37 2

6 1/2 (inter-uterine) 145.35 137.90 157.60 4

5 361.61 330.35 - 410.00 16

7 391.22 391.22 1

9 415.48 399.00 - 431.97 2

10.5 450.53 444.17 - 456.90 2

17 551.77 509.22 - 603.02 19

19 550.38 544.65 - 556.12 2

20 562.65 562.65 1

21 561.61 551.27 - 571.95 2

29 623.97 601.50 - 645.22 14

34.5 630.07 630.07 1

41 664.39 632.57 - 678.77 8

45 665.22 660.20 - 665.22 2

46 689.90 689.90 1

53 711.96 693.87 - 738.05 4

65 739.27 736.55 -742.00 2

69 730.60 730.60 1

77 766.96 763.77 - 770. 15 2

89 794.78 786.87 - 804.92 3

101 827.70 827.70 1

113+ 857.50 857.50 1

20·

900r----------...........- __

(J)

~a: C)

..J=400 ~

~

.... 30 I C)

1&1

~ 200 (J)

Z 1&1 ..J 100

800

700

600

500

Figure 8. Growth-rate curve of the lens of the antelope eye.

1000r------------------------------,

y. 2.60X + 545.44 mg.

900 r· .995

800

/J)

z 700 W ..J

AGE IN MONTHS

~igure 9. Enlarged portion of the latter part of the growth-rate curve of the lens.

TABLE VI

COMPARISON OF WET WEIGHTS, VOLUME AND DRY WEIGHTS OF THE ANTELOPE LENS

Age Class Wet Weight _ Range _~_ Y~J...,'!1~ Range Dry Weight Range

S.D. S.E. S.D. S.E. S.D. S.E.

5 mos. 72.3 18. 1 882•80 - 1189.25 68.6 17•2 792. 10 - 1081.85 17•8 4.5 330.35 - 410.00

17 mos. 91.2 21.0 1317.70 - 1667.85 83.9 19.2 1168.20 ...· 1497.32 26.7 6.14 509.22 - 603.02

29 mos. 76.3 20.4 1563.70 1798.02 (J} .7 18.6 1395.70 - 1617.72 15.0 4.01 601.50 645.22

41 mos. 92.7 32.8 1650.90 1963.55 89•8 31.7 1476.60 - 1775.17 11.6 4.10 632.57 678.77

53 mos. 80.8 40.4 1841.85 2019.57 77.6 38.8 1645.45 1813.17 18.9 9.45 693.87'" 738.05

65 mos. 2002.37 - 1992.52 1793.10 1795.07 736.55 742.00

77 mos. 2018.40 - 2090.40 1806.80 1880.60 763.77 770. 15

89 mos. 128.4 74.2 1874.20 ... 2122.52 127.2 75.5 1655.30 -1899.17 9.2 5.33 786.87 804.92

101 mos. 2342.85 2122.05 827.70

113+ mos. 2264.87 2023.42 857.50

.....,-

22

Lens growth during the second period from five months to three and one-half

years remains rapid, but the rate slowly decreases as age progresses (the negative

acceleration phase). Thus, the increment is 190.16 mg. from five months to one and

one-holf years, but only 40.42 mg. from two and one-half to three and one-half years.

Using these data, a regression value (b) of 8.20 mg. increase per month or 98.40 mg.

increase per year was obtained. The derived equation for this period is:

Y =8.20 X + 527.44 mg.

where X = estimated age in months. The correlation value (r) of .947 is not significant

at either the five or the one percent level.

During the last phase from three and one...half years onward, the rate of lens

growth remains approximately steady. The regression value and derived equation for

this period will be discussed later.

A compcrlson of the increment rate shows lens weight increased by 52.6

percent from five months to one and one-half years; 13. 1 percent from one and one­

ha If to two and one-hal f years] 6.5 percent from two and one-ha If to three and one­

half years and 7.1 percent from three and one-half to four an-d one-half years. After

four and one-half years the rate of increase is approximately 3.8 percent per year.

The aging of specimens three and one-half years of age or younger is

compcrctlvely easy, as differences in lens weights between the various age classes

are large and the amount of lens weight overlap between age groups is small. No

overlap occurred between the five months to one and one-hal f year old classes.

Between the one and one-half to two and one-half year old groups, there was one

instance in which the heaviest lens from the younger age group weighed approximately

1.5 mg. more than the lightest lens in the older age group. Similarily, the heaviest

lenses In the two and one-half year old group weighed slightly more than the lightest

lens in the three and one-half year old class. Up to this age, the amount of lens weight

overlap is so small that erroneous placing of specimens into their respective age classes

would occur in only a few cases. ThIs small amount of overlap in lens weights lends

strong support for the use of the lens as a reliable index of age.

The critIcal stage in age estimation is reached after three and one-half years,

23

when the amount of increase in lens weight between the various age classes is

considerably less, thus allowing a smaller margin for variability and overlap. The

values of weight on age, or Y on X, from three and one-half years onward approx­

imates a straIght line, with a regression value (b) of 2.60 mg. increase per month, or

31.20 mg. increase per year. The correlation value (r) of .995 is highly significant.

The derived equation is:

Y =2.60 X + 545.44 mg.

where X = esHmated age in months.

To illustrate this more clearly an enlarged portion of the latter Part of the

growth-curve of the lens (Figure 8) Is shown in Figure 9. This shows a hIgh correlation

between lens weight and age. ExtensIon of the curve In Figure 9 allows one to estimate

the expected lens weights for animals older than eight and one-half years. This exten­

sion is felt to be [usflfled, as the oldest specimen under study (estImated to be older than

nlne and one..half years) possessed the heaviest lens (857 ~57 mg.). This lens weight is

not plotted on the curve"as the dental criteria used in assigning ages to each specimen

did not allow agIng of animals older than nine and one-half years.

To simplify age calculation a chart has been prepared showing approximate dry

weights of lenses and corresponding age groups (Table VU).

Four of the specimens showed wide discrepancies between ages as calculated

by the iaws and those determined by the lenses. In three out of the four cases, dentitIon

showed the specImens to be older than did the lens weIghts. It was felt that excessive

tooth wear In these three older age anImals led to their ages being over--estimated when

using dentition as the age Index. The single specimen where the reverse situation

existed had abnormally long teeth with an uneven wear pattern, which probably accounted

for its age being under--estimated on the basis of dental criteria.

In the above four cases where these wide dIscrepancies existed, radiograms of

the lower iaw I which show a decrease In root length with an increase in age, were

used to help verify the assigned ages. Out of the above four samples, one radiogram

supported the age as determined by the lens and three supported the ages as estImated

by external dentition. This suggests that age estimates based on external dental characters

24

are probably as reliable as techniques whIch measure decreases in root length by

means of X-ray photographs.

25

TABLE VII

CHART TO BE USED TO ESTIMATE AGES OF ANTELOPE

WHEN DRY WEIGHTS OF LENSES ARE KNOWN

Approximate Dry Estimated Age Mean of Each Weight of Lenses (mg.) Range (months) Group (actual values)

250 ... 450

460 -575

575 - 645

645 - 690

690-725

725 -755

755 -785

785 - 815

815 - 845

Birth to 10 mos.

11 to 23

23 to 35

35 to 47

47 to 59

59 to 71

71 to 83

83 to 95

95 to t07

Age (months)

5

17

29

41

53

65

77

89

101

Lens Weight (mg.)

361.61

551.77

623.97

664.35

711.96

739.27

766.90

794.78

827.70

Ages of animals older than 107 months can be calculated by adding

approxImately 30 mg. per year to heaviest known lens weight.

26

DISCUSSION

The vertebrate lens is a more reliable index of the ages of antelope than

are dental characters and horn growth. Only male antelope have horns which are

long enough to measure, and there is so much local variation in horn size that this

character can only be used to separate [uvenlles from adults.

Changes in dentition occur with age, regardless of sex, but the measurable

changes are in most cases ebrupt, rather than continual I and are subject to various

environmental influences. Tooth eruptIon and replacement! for example, occur at

intervals. Animals aged on this basis can be assigned to age classes, but the absolute

age of the anlmal in months or weeks cannot be determIned. The teeth of antelope

living In areas of sandy soil tend to wear more rapidly than those of anImals in habitats

where clay or loam is the predominant soil type. In a study of the development and

wear of teeth of mule deer, Robinette et ~ (1957) found that small fragments of rock

and sand frequently become lodged in the infundibula of the teeth, and the abrasion

of these particles is liable to cause excessIve tooth wear. Environmental influences

of this sort are more noticeable in older animals, but they also affect younger animals

as well. These Influences require that the sources of environmental variabilIty be

known before accurate estimates of age can be made.

The lens of the eye grows at a rate whIch is predictable, wIthin reasonable

limits, for any age and the rate of growth is not subject to environmental influences

or the physical condltlon of the animal. Rats fed on deficIent diets and subjected to

severe malnutrition showed the same rate of lens growth as controls on normal diets

(Pirie, 1948).

Because of the predictable rate of increase in lens size, animals can be

aged more accurately according to this character than they can with any other

available criterion. Dental characters cannot be used during the period from

conception to birth, but data obtaIned durIng this study suggest that reasonably

accurate estimates of age can be made during the latter part of the gestation period.

In the period from birth to about three and one-half years of age I dental characters

are reasonably accurate in terms of age classes, but the use of the lens allows fairly

27

reliable determinations within limits of about a month of age. The reliabi Uty of

dental characters decreases after the age when tooth replacement is complete.

During this period the rate of lens growth is slower and there is considerably more

overlap in lens sizes between animals of different ages J but the rate of growth is

constant and predictable and estimates of age can be made beyond the stage when

dental characters are applicable.

The data obtained during this study were, unfortunately, based upon random

samples from natural populations in which none of the ages of the animals was known.

Thus the lens measurements had to be correlated with estimates of age based on dental

characters and are subject to the same sources of error. However, it has been demon­

strated that lens growth proceeds at a species-predictable rate in antelope and the

growth curves that have been established in this study can be verified when tagged

specimens of known age are available.

28

SUMt-AARY

1. A study was made of the relationship between the age of pronghorn

antelope (Antilocapra americana) and the size of the corneal volume of the lens,

wet weight of the lens and dry weight ofthe lens. Data were obtained from 92

antelope and 13 fetuses coli ected throughout the Province of Saskatchewan at

different seasons of the year.

2. Ages were assigned on the basis of external dentition and radiograms

of the lower jaw.

3. The increase in dimensions of the cornea is relatively slow and there is

almost a complete cessation of growth at about two years of age, so that this character

is not a satisfactory index of age.

4. The volume, specific gravity and wet weight of the lens show relatively

consistent increases with age I but these values are less reliable than the dry weight

of the lens as indicators of age.

5. The most consistent values, with the least amount of variability within

age classes and the least overlap between age classes were obtained from dry weights

of the lenses. The rate of lens growth, based on dry weights, showed extremely rapid

growth up to the age of 5 months; there was a gradual decrease in rate between 5

months and 4 1/2 years of age, with the inflection of the growth curve at about 28

months of age} the rate of growth from 4 1/2 years of age to 8 1/2 years I the oldest

animal for which data were avallable, was remarkably constant.

6. The dry weight of the lens of the eye appears to be a convenient and

reliable index of the age of antelope, but data from animals of known age are required

before the growth rates established in this study can be used with confidence.

29

LITERATURE CITED

AdlerIF. H. 1953. The physIology of the eye (clinical application). The C. V.

Mosby Company. 734 pp.

Bellows, John G. 1944. Cataract and anomalies of the lens. St. Louis, The C. V.

Mosby Company, 624 pp.

Dow, SeA. 1955. An evaluation of some criteria for age determination of the

pronghorn (Antilocapra americana Ord.). Unpublished M.S. thesis"

Montana State University.

Lansing, Albert I. 1952. Cowdry's problems of aging. Baltimore: Williams and

Wilkins cs., 1061 pp.

Lord, R. D. Jr. 1959. The lens as an indicator of age in cottontail rabbits. Jour.

of Wildlife Mgt., 23 (3): 358-360.

. 1961. The lens as an indicator of age In the gray fox. Jour. of--.......--­Mammal., 42 (1): 109-111.

Murie, Adolph. 1944. The wolves of Mount McKinley. U.S. Dept. Interior,

Nat. parks Serv , , Fauna Natl. Parks, U.S. Fauna Sere No.5.

RobInette, W. Leslie; Dale A. Jones; Glenn Rogers; and Jay S. GashwHer. 1957.

Notes on tooth development and wear for Rocky Mountain Mule Deer.

Jour. of Wildlife Mgt. t 21 (2): 134-153.

Scammon, Richard E. and Meredith B. Hesdorffer. 1937. Growth in mass and volume

of the human lens In postnatal llfe , Archives of Ophth., 17 (1): 104-112.

Scheffer, V.B. 1950. Growth Layers on the teeth of Pinnipedia as an indicator of age.

Science, 112: 309-311.

30

Sergeant, D. E. and Douglas H. Plmlott, 1959. Age determination in moose from

sectioned incisor teeth. Jour. of Wildlife Mgt., 23 (3): 315-321.

Wanko, T. and Mary Gavin. 1959. Electron microscope study of lens fibers.

J. of Biophysic. and Blochem, Cytol., 6 (1): 97-101.

Date Jaw CharacteristIcs of teeth Used In EstablIshingAg~ c~lasses _ EstImated ColLected Number Sex 11 12 13 ~. P2 P3 P4 M1 M2 M3

Age

Oct. 31 K-l M D D D D D D D P 5 months II K-2 F It I( II It It It It It It

.. K-3 F It It If ... It II II It ALC-2 ABC-2

PLC-2 PBC-2

It

It K-4 M II U It It It II Il It ALC...2 ABC-2

It

It

tI

K-5

K-6

F

M

It

It

u

tl

It

It

II

It

It

It

It

It

It

Il

II

II

ALC-2 ABC-2

II

Il

»­." ." mz_ .. K-7 F .. II It It It .. Il II It o X

.0­

It K-8 F .. II .. II It II II II It

II K-9 M It It It It II It .. II ALC-2 ABC-2 PBC-2

II

.. K-I0 F Jaw missing (Lens only) It

It K-l1 M D D D D D D D P ALC-2 ABC-2

It

11 K-12 M u II II II .. II It II ALC-2 It

ABC-2

II K-13 M II It II II II II It It ALC-2 PLC-2 ABC...2

Il

It K-14 F Jaw missing (Lens only) fI

II K-15 F Jaw missing (Lens only) If

II K-15(a) M Jaw missing (Lens only) II

Dec. 30 K-72 F D D D D D D D P ALC-2 PLC-2 ABC-2 PBC-2

7 months

Feb. 21 K-80 F II It .. II II It It II II 9 months

Date Jaw Estimated Collected Number Sex 1 1 C P P M M M Age11 2 3 1 2 3 P4 1 2 3

Feb. 22

Apr. 15 It

K-82

K-90

K-91

F

M

F

D

H

•

D

It

It

D

II

Il

D

.. tI

D

.. II

D

II

tl

D

tI

II

P

U

It

ALC-2 PLC-2 ABC-2 PBC-2

P II

ALC-2 ABC-2

9 months

10.5 months

II

M2 .. IndIcates number of crests of both right and left M2 erupted through gumt

-:::::­_. .........

ALC anterior lingual crest, ABC - anterior buccal crest

PLC posterior lingual crest! PBC ... posterior buccal crest

Date Jaw Collected Number Sex 11 12

13 C1 P2 P3 P4 M] M 2

M 3

Estimated Age-

Oct. 31 K-16 M P D D D D D D P P P 17 months

If K-17 F If II II If II II II It It .1 It

II K-18 F .. II II II II II It II II It It

II K-19 F II .. II II II 11 II II It II It

It K-20 M u It II H II .1 II It U II II

It K-21 F If II I. II II II It II II II II

It K-22 F II II II II It II II II II n fl

It K-23 F II II II .. II II II It II It II -II K-24 F II 1I II I( II It .. II It U II e-

II K-25 M .. II It .. II I' II II II II II

II K-26 M If II II II It II II II II II It

II K-27 M It II II II Remainder of law missing

If K-28 F tl II II It D D D P P P II

II K-30 F It If II II Il It II It It II II

II K-31 M u II. fl II II It It II II U It

It K-32 F II II .. II II II II It II II It

It K-33 F Jaw missing (lens only)

II K-34 F P D D D D D D P P P .. Ii K-35 F II II It It It II If II II .. It

Date Collected

Jaw No. Sex 11 12 1

3 C1 P2 P3 P4 M) M2 M

3

Estimated Age

Dec. 22

Dec. 30

Jan 28

K-73

K-74

K-n

M

F

F

P

Right-D Left-P

P

D II

II

D II

It

D II

Il

D II

II

D M

JI

D Jl

..

P II

Il

P tl

It

P II

u

19 months ..

20 months

f'.Aar. 1 K-84 M II Jt If II tl II II II Il II 21 months It K-85 M tl II II 11 Il It II II It Jl Jl

Oct. 31 II

It

K-36

K-37

K-38

F

F

F

P II

It

P II

It

P

D

P

D It

missing

P

missing

P

P II

II

P Il

II

P It

II

P JI

..

P Jl

Jl

29 months II

II

--._. .s,

It

It

K-39

K-40

F

M

II

u

Jl

II

Right-D Left-P

D

D

II

II

II

It

II

II

II

II

II

II

.. II

..

II

II

II

II

K-41

K...42

F

M

If

It

II

II

P

D

D

D

It

II

II

It

Jl

It

II

II

U

.. II

II

It

It

II K-43 F II II II It beginning to erupt

II Right-P Left-D

11 Jl " II

It K-44 F It II P II P II P It It It Il

II

II

II

K-45

K-46

K-47

F

F

F

tl

..

..

II

..

II

D It

P

If

II

It

II

Left-absent Right-P

P

It

II

II

It

II

II

II

II

II

II

..

Il

n

II

II

It

II

It

Date Collected

Jaw No. Sex I) 12 13 C1 P2 P3 P4 M 1 M2 M3

Estimated Age

Oct. 31

.. April 15

K-52

K-53

K-92

F

M

F

P

It

II

P

II

II

P

.. II

beginning to erupt

D

D

absent

missing

P

P

Il

tl

P

Il

II

P

It

It

P

Il

II

P

II

It

29 months

II

34.5 months

Oct. 31 K-48 F tl II It P It II Il It Il II 41 months II

Il

u

K-49

K-50

K-51

M

F

F

It

II

It

II

I(

It

Il

It

It

II

D

Right-D Left-P

11

12

infundibula II

lnfundibula

u

.. it.. -.s,

I( K-64 F It It It P I( It

II K-66 F II It It It 11 Infundibula n

II K-67 F JI II u- II It II

II K-55 M It II It II II II

Feb.. 22

Mar. 1

Mar. 28

K-83

K-86

K-88

M

M

F

Jt

tl

II

If

II

II

II

II

It

D

missing

P

12

II

infundibula Il

45 months II

46 months

Oct. 31 II

K-54

K-69

M

F

P t1

P H

P It

P ..

9 infundibula

10 infundibula

53 months II

Date Jaw Estimated Coliected No. Sex I] 1 1 C P2 f P M M M Age2 3 1 3 4 1 2 3

Oct. 31 K-78 F P P P P missing 10 infundibula 53 months

tI K-79 F II I( "­ .. P II It

Dec. 30 K-75 F It U II If It 9 infundibula 55 months

Oct. 31 K-62 F P P P P 7 i n.Fu n d i bu I a 65 months

II K-76 M H It II II II H

Mar. 28 K-87 M II .. ., 1·1 6 Infundibula 82 months

Oct. 31 K-60 F II JI U If 6 infundibula 77 months ~e-

u K-61 M I. If If .. 5 infundibula If

If K-57 M II fl II Jl It It

If K-65 F II II II It 6 infundibula .t

u K-68 F If It II It 4 infundibula 89 months

.. K...71 F II II II .. 3 or 4 infundibula II

It K-63 F n Jt It II U

II K-59 F .. II .. II 3 infundibula Il

Feb. 21 K-81 M It &I II If 3 or infundibula 93 months

Oct .. 31 K-70 F II Jl .. II 2 or 3 infundibula 89 to 101 months

H K-58 F It II II It 1 infundIbula 101 months

Apr. 14 K-89 F II Jl tI II II 106.5 months

If It If N 0 i n fun d I bu I a 113+ months Oct. 31 K-29 F II

=

3 Date Lens Estimated Dry Weight (mg.) Wet Weight (mg.) Volume (rnm.] Specific

Collected Number Sex Age (mcs.) Right Lens Left Lens Right Lens Left Lens Right Lens Left Lens Gravity

-----Dec. 30 K-75 M 3 (inter-uterine) 15.35 15.10 72.15 70.45 65.75 63.9 1.1060

.. 11 F If 16.10 15.90 70.85 69.50 61.65 62.90 1.1268

Jan. 28 K·~c77 M 4 [Inter-uterine] 41.20 41.40 168.45 167.25 154.05 151.05 1.1003 It II F It 40.25 40.10 162.35 161.40 144.55 145.20 1.1173 II K-78 M It 54.50 54.60 2J7.-15 219~50 197~15 200.95 1.0968 It If F It 51.60 50.95 211.85 208.00 196.05 191.80 1.0825 It K-79 F It 36.65 36.65 155.70 152.10 142.30 139.50 1.0922 »­

""tJ

Mar. 28 ..

Apr. 14

K-88 II

K-89

M

F

M

6 (i nter-uterine)

••

6 1/2 (inter-uterine)

110.60

116.10

158.05

112.55

120.65

157.15

428.75

431.25

551.40

434.60

431.35

538.70

399.15

396.05

499.00

402.40

397.35

492.90

1.0771

1.0872

1.0990

." m z..-..< oX -­-

It II M II 145.60 143.90 521.40 521.00 476.40 475.20 1.0954

Apr. 15 K-92 F II 141.15 134.65 515.20 526.65 473.70 482.05 1.0900 If " F It 135.30 146.70 516.50 507.10 472.90 462.50 1.0942

Oct .31 K-l M 5 349.05 347.05 1013.30 1033.95 902.70 932.95 1.1152 .. K-2 F If 37] .55 371.95 1022.20 1031.67 914.80 936.67 1.1093 ,. K-3 F at 359.30 356.95 1073.70 1109.75 973.70 1007.65 1.1020 II K-4 M " 340.05 339.00 996.80 993.90 898.40 896.50 1.1090 tl K-5 F II 363.50 362.55 1006.70 1002.00 903.50 897.00 1.1156 tl K-6 M .. 357.40 357.05 1082.35 1031.25 980.95 927.65 1.1074

Date Lens Estimated Dry WeIght (mg.) Wet Weight (mg.) 3

Volume (mm.) Specific Collected Number Sex Age (mos.) RIght Lens Left Lens Right Lens Left Lens Right Lens Left Lens Gravity

Oct. 31 K-7 F 5 361.45 360.35 1097.80 1105.30 997.40 1001.90 1.1019 II K-8 F If 366.20 365.35 1028.15 1052.45 923.75 949.05 1.1109 .. K-9 M .. 356.50 357.40 993.65 994.90 890.65 892.70 1.1156 tt K-IO F II 329.90 330.80 876.90 888.90 786.30 797.90 1.1146 It K-l1 M tt 368.70 370.05 1042.10 1029.10 939.50 925.90 1.1103 If K-12 M It 410.75 409.25 1154.60 1198.35 1042.20 1083.55 1.1068 II K-13 M I' 349.05 352.05 1028.70 1052.50 930.50 953.70 1.1045 -II K....14 F II .... 380.65 ......' 1189.25 - ]081.85 1.0992

~.-­--II K-15 F II 369.40 367.30 1044.85 1038.50 944.05 936.50 1.1084 It K-15(a) M If - 365.20 .... 1013.85 - 912.05 1.1116

Dec. 31 K...72 F 7 393.55 389.10 ]293.20 123] •15 ]182.40 1118.95 1.0970

Feb. 21 K-80 F 9 398.50 399.50 1198.00 1198.85 1085.00 1113.05 1.0904

Feb. 22 K--82 F It 435.65 428.30 1398.20 13]3.50 1286.20 1199.10 ] .0988

Apr. 15 K-90 M 10.5 438.55 449.80 1496.00 1421.60 1366.60 1298.20 1.0948 II K-91 F II 448.25 465.55 1526.40 1524.60 1393.40 1404.40 1.0904

Oct. 31 K-16 M 17 564.50 564.45 1525.50 1532.45 1368.70 1377.45 1.1135 II K-17 F .. 603.95 602.20 1653.55 1682.15 1482.90 1511.75 1.1138 II K-18 F II 515.65 515.70 1409.00 1421.35 1266.40 1274.75 1.1138 I. K-19 F II 580.30 579.50 1517.70 1513.35 1353.30 1353.35 1.1198 II K-20 M II - 521.80 - 1441.90 - 1294.70 1.1136

Date Lens Estimated Dry Weight (mg.) Wet Weight (mg.) 3Volume (mm.) Specific Collected Number Sex Age (mos.) Right Lens Left Lens Right Lens Left Lens Right Lens Left Lens Gravity

-Oct. 31 K-21 F 17 537.60 536.40 1467.25 1508.85 1317.85 1356.15 1.1129

at K-2.2 F u 566.35 - 1480.80 - 1319 •. 40 ... 1. 1223 It K-23 F .. 544.90 544.00 1460.90 1468.35 1312.75 1313.95 1.1151 It K-24 F II 528.10 531.25 1454.30 1451.00 1305.00 1301.00 1.1148 If K-25 M II 533.25 533.40 1434.80 1428.80 1289.40 1278.00 1.1153 II K-26 M II 584.65 582.45 1565.00 1544.65 1398.80 1376.65 1.1204 II K-27 M It 535.90 536.80 1311.10 1324.30 1161.70 1174.70 1.1279 II K-28 F II 574.10 576.90 1588.05 1650.15 1425.25 1485.95 1.1123 "C

c.. .. K-30 F II 520.95 520.35 1416.30 1493.00 1271.30 1347.20 1.1110 tl K-31 M II 566.25 - 1569.05 - 1411.85 ..­ 1.1113 II K-32 F .. 582.15 .... 1609.65 ....... 1446.05 .... 1.1131 tl K-33 F It 553.05 553.80 1463.50 1462.30 1313.30 1307.50 1.1163 It K-34 F .. 509.00 509.45 1411.25 1438.00 1269.45 1293.00 1.1119 If K--35 F Jt 562.05 559.70 1629.75 1660.55 1474.35 1505.55 1. 1041

Dec. 22 K-73 M 19 541.65 547.65 1704.40 1617.40 1551.40 1465.00 1.1012

Dec. 30 K-74 F It 558.55 553.70 1574.50 1577.30 1418.70 1427.30 1.1074

Jan. 28 K-77 F 20 564.25 561.05 1704.85 1676.55 1546.65 1517.75 1.1034

Mar. 1 K--84 M 21 562.40 548.15 1616.30 1656.10 1457.90 1523.30 1.0976 If x-es M .. ..... 571.95 - 1667.70 - 1507.10 1.1065

Date Lens Estimated Dry WeIght (mg.) Wet WeIght (mg.) 3

Volume (mm.) SpecIfic Collected Number Sex Age (mos.) Right Lens left lens RIg ht Lens Left Lens RIght Lens Left Lens Gravity

Oct. 31 K-36 F 29 639.85 -­ 1755.70 ..... 1572.90 - 1.1162 II K.-37 F II 615.75 601.80 1682.30 1798.10 1510.10 1628.10 1.1090 II K-38 F 'f 632.75 613.30 1717.00 1672.20 1537.40 1502. 18 1.1150 It K-39 F II 634.15 639.05 1739.90 1755.85 1560.50 1580.05 1.1131 u K-40 M II 617.15 616.20 1606.65 1601.25 1436.65 1431.25 1. 1185 If K-41 F Jf 606.65 608.75 1623.80 1659.90 1452.20 1489.82 1. 1161 I. K-42 M .. 603.05 599.95 1565.60 1560.80 1399.40 1392.00 1.1203 If K-43 F •• 644.50 645.95 1670.60 1657.85 1490.60 1479.05 1.1208 ,-...

x-If K-44 F It 627.20 630.30 1678. 15 1661.00 1506.95 1486.60 1.1154 If K-45 F It 611.40 61 t .20 1605.05 1572.15 1432.85 1405.55 1.1193 .. K-46 F It 634.80 640.45 1806.50 1789.55 1626.70 1608.75 1.1114 II K-47 F Jt 643.25 643.30 1738.90 1736.95 1561.70 1555.75 1.1150 at K-52 F It 605.50 609.45 1716.90 1606.35 1546.90 1436.35 1.1139 tt K-53 M It 631.85 623.75 1751.85 1690.70 1572.85 1514.90 1.1149

Apr. 15 K-92 F 34.5 619.55 635.45 1841.70 1853.45 1667.50 1683.45 1.1027

Oct. 31 K-48 F 41 - 663.60 - 1758.40 - 1577.20 1.1148 ft K-49 M II 656.10 665.20 1803.66 1789.00 1619.06 1599.00 1.1164 Il K-50 F It 680.75 676.80 1904.30 1848.55 1713.90 1659.85 1.1123 If K-51 F II 651.40 651.85 1825.55 1675.05 1644.35 1495.05 1.1150 It K-64 F 'I 672.75 676.20 1775.60 1754.55 1585.60 1564.95 1.1204

Date Lens Estimated Dry Weight (mg.) Wet Weight (mg_) 3Volume (mm.) Specific Collected Number Sex Age (mos.) Right Lens Left Lens Right Lens Left Lens Right Lens Left Lens Gravity

Oct. 31 K-66 F 41 628.30 636.85 1664.65 1637.15 1491.05 1462. 15 1.1180 I. K-67 F Il 677 .20 679.00 1972.55 1954.55 1784.39 1765.95 1.1061 If K-55 M II 673.85 676.90 1793.55 1773.50 1603.55 1590.30 1.1168

Feb. 22 K-83 M 45 663.30 669.10 1913.45 1841.55 1733.05 1655.75 1.1080

Mar. 1 K-86 M II - 670.25 - ]789.55 - 1600.75 1.1179

Mar. 28 K-88 F 46 683.55 696.25 1951.30 1967.25 1761.50 1775.25 1.1079

.--... x

--:;.

Oct. 31 K-54 M 53 697.05 690.70 1854.50 1829.20 1656.50 1634.40 1.1193 II K-69 F It 736.05 740.05 2007.05 1950.05 1806.25 1743.65 1.1147 II K-78 F .. 712.40 - 2039.25 ....... 1820.25 - 1.1203 II K-79 F •• 701.75 705.30 2019.35 1983.55 1821.75 1784.55 1.1099

Dec. 30 K..75 F 55 744.35 736.20 2006.65 1987.50 1799.65 1780.70 1.1155

Oct. 31 K-62 F 65 737.10 736.00 2088.40 1916.35 1882.20 1707.95 1. 1154­tt K-76 M If - 742.00 ..... 2052.20 - 1850.00 1.1112

Oct .31 K-60 F 77 763.35 763.45 2008.95 2027.95 1795.15 1817.45 1.1171 u K-61 M 1& 769.75 770.55 2101.65 2079.15 1897.85 1863.35 1.1115

Date Collected

Lens Number Sex

Estimated Age (mos.)

Dry Weight (mg.) Right Lens Left Lens

Wet Weight (mg.) Right Lens Left Lens

3Volume (mrn.] Right Lens Left Lens

Specific Gravity

Oct. 31 II

fWJr. 28

Oct. 31 II

Jf

at

Feb. 21

Oct. 31 It

Apr. 14

K-57

K-65

K-87

K-68

K-71

K-63

K-59

K-81

K--70

K-58

K-89

M

F

M

F

F

F

F

M

F

F

F

77 If

82

89

" .. If

93

89 to 101

101

106.5

No lens

No lens

806.00

781.45

790.55

No lens

-No lens

No lens

802.40

803.85

792.30

794.55

730.60

853.00

2104.70

2059.70

1861.85

-

2394.85

2140.35

2051.00

1886.55

2059.65

2290.85

1881.30

1843.30

1644.05

-...

2170.45

1917.05

1836.50

1666.55

1874.45

2073.65

1.1176

1.1170

1.1322

1.0941

1. 1040

-~...-

Oct. 31 K-29 F 113+ 855.95 859.15 2263.80 2265.95 2022.70 2024.15 1.1193