NORTHWESTERN UNIVERSITY LIBRARY Manuscript Theses Unpublished theses submitted for the Master’s and Doctor's degrees and deposited in the Northwestern University Library are open for inspection, but are to be used only with due regard to the rights of the authors. Bibliographical ref­ erences may be noted, but passages may be copied only with the permission of the authors, and proper credit must be given in subsequent written or published work. Extensive copying or publication of the thesis in whole or in part requires also the consent of the Dean of the Graduate School of Northwestern University. . ,, . . H. S. WINN This thesis b y ................................... . has been used by the following persons, whose signatures attest their acceptance of the above restrictions. A Library which borrows this thesis for use by its patrons is expected to secure the signature of each user. NAME AND ADDRESS DATE - ProQuest Number: 10102145 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. uest, ProQuest 10102145 Published by ProQuest LLC (2016). Copyright of the Dissertation is held by the Author. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code Microform Edition © ProQuest LLC. ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106 - 1346 NORTHWESTERN UNIVERSITY LIBRARY Manuscript Theses Unpublished theses submitted for the Master’s and Doctor’s degrees and deposited in the Northwesterh University Library are open for inspection, but are to be used only with due regard to the rights of the authors. Biblio­ graphical references may be noted, but passages may be copied only with the permission of the authors, and proper credit must be given in subsequent written or published work. Extensive copying or publication of the thesis in whole or in part requires also the consent of the Dean of the Graduate School of Northwestern University. Theses may be reproduced on microfilm for use in place of the manuscript itself pr yided the miles listed above are strictly adhered to and the rights of the author arv. in no way jeopardized. This thesis by . 7 ............. has been used by the following persons, whose signatures attest their accept­ ance of the above restrictions. A Library which borrows this thesis for use by its patrons is expected to secure the signature of each user. NAME AND ADDRESS DATE NORTHWESTERN UNIVERSITY EFFECTS OF DIFFERENT PHOTOPERIODS ON BODY WEIGHT, FAT DEPOSITION, MOLT, AND MALE GONADAL GROWTH IN THE SLATE-COLORED JUNCO. A DISSERTATION SUBMITTED TO THE GRADUATE SCHOOL IN PARTIAL FULFILLMENT OF THE REQUIREMENTS for the degree DOCTOR OF PHILOSOPHY FIELD OF ZOOLOGY By Hudson Sumner Winn EVANSTON, ILLINOIS June, 1950 TABLE OF CONTENTS Acknowledgment INTRODUCTION Review of Literature ...... ......... 1 Development of Experimental Plan........ 15 MATERIALS AND METHODS The Experimental Subject........................... 20 Trapping............................................22 Banding ...... 23 Maintenance Prior to Start of Experiments..........24 Segregation at Start of Experiments. ..... 26 Procedures: 1. Maintenance ...... 30 2* Periodic Observations .......... ..30 3. Sampling........................... 31 4. Measurements of Testes......... 32 5. Histologic Technique .................32 RESULTS Body Weight and Fat Deposition.....................34 Molt................................................37 Testis Development........... 39 DISCUSSION AND CONCLUSIONS Body Weight and Fat Deposition..................... 43 Molt .............. 48 Testis Development................................. 52 SUMMARY......... 57 LITERATURE CITED VITA TABLE OF CONTENTS (Continued) LOCATIONS OF TABLES AND FIGURES IN TEST Following page Table 0, Photometer Readings in Foot-candles.........29 Table 1, Body Weights Prior to Experiments...........34 Figures 1-12, Body Mean Weights and Fat Classes......34 Table 1A, Chronology of Weight-Fat Response..........36 Figure 13, Times of Fat Deposition by Majorities of Responding Birds.................... ...36 Figure 14, Sequence of Fat Deposition, Fat Loss, and Molt .......................... 39 Tables 2-7, Testis Data,......... 39 Figures 15-20, Testis Weights and Stages of Develop-- ment................................... 40 APPENDIX Tables 8-19, Body Weights and Fat Classes Table 20, Dates Equivalent to Days After Start of Experiment Plates 1-6, Experimental Rooms and Equipment ACKNOWLEDGMENT I wish to express my sincere appreciation to Dr. Albert Wolfson, who suggested this problem and under whose guidance the research was conducted. His generous assist­ ance and enthusiastic counsel during the course of the research and the preparation of the manuscript are grate­ fully acknowledged. 1 INTRODUCTION Review of the Literature Man has teen curious about migrations undertaken by many species of birds ever since he first noticed their seasonal appearances and disappearances. Because migratory activity was observationally associated with certain seasons of the year, man has attempted to correlate such activity with recognizable factors of the external environment. But observational data have led to conflicting conclusions. Though numerous clues have been revealed, making certain environmental factors suspect, the inherently limited poten­ tialities of observational data alone, have prevented an elucidation as to how those factors might operate. The use of an experimental approach to this problem was initiated by Rowan (in 1924 e_t sea. Y. He demonstrated that it was possible to cause precocious gametogenesis in juncos by subjecting them to photoperiods of gradually increasing durations at the time of year when the gonads have reached their annual minimum in size and activity. Rowan extended the short, natural, fall and winter photoperiods with periods of artificial illumination. Various modifications of this technique have been employed by subsequent investigators to manipulate the gonadal cycles of a wide variety of birds and other vertebrates, providing indisputable evidence that light affects the gonads. Among the other factors of the external environment which have been considered is temperature. The potentially impor­ tant role that temperature might play as a causative influence 2 in seasonal reproduction among birds is considerably diminish­ ed by the fact that Rowan fs (1989) initial experiments were conducted during the Canadian winter at subzero temperatures* The lowest temperature he recorded was -52° F. Riddle (1925) reported that reproduction in pigeons is depressed by cold, but Bissonnette and Csech (1937) hatched pheasant chicks on Christmas Day, following a period of light experimentation. Kendeigh (1941) reported no significant differences in re­ productive response between English sparrows kept at 36° F. and at 72° F. Burger (1948) stated that the testes of star­ lings maintained between 90°F. and 100° F. were much larger than the testes of starlings kept at lower, varying tempera­ tures, when both groups were exposed to photoperiods of long duration. The higher temperatures, however, did not induce continued spermatogenesis when the duration of the photo­ period was reduced. Burger concluded that external tempera­ tures approximating the body temperature of the Starling neither suppress spermatogenesis nor cause regression of the testis. These and similar additional records in the literature show that external temperature exerts no prohibitive effect on the gonadal development of most of the birds studied. Once the breeding condition is attained, however, temperature has been shown to be correlated, at least in some birds, with egg size and number (Kendeigh, 1941; Lee, Robinson, Yeates, and Scott, 1945). There is no evidence, on the other hand, to indicate that temperature is responsible for the initiation 5 or the maintenance of progressive gonadal development, such as that resulting from light experiments. As far as is known, food, adequate in content and amount, plays no important role in the sexual development of season­ ally reproducing birds. Food that is deficient in known es­ sentials might be expected to produce metabolic abnormali­ ties among birds, but in such instances, food is acting only as a limiting factor in the matter of gonadal development. Bissonnette (1932b) maintained starlings on a low protein diet and found no sexual response even though the birds were exposed to photoperiods of long duration. Kendeigh (1941) compared testicular responses in English sparrows, some of which were permitted to feed only during restricted periods, and others during the whole light period. The amount of food consumed was the same in each instance, and there was no dif­ ference in testicular response. No evidence exists in the literature to confirm the possibility that a specific ingre­ dient of food might activate birds sexually. There can be no doubt that in the external environment many supposed and actual factors exist which have not been considered here. Their characters and their degrees of pos­ sible influence on gonadal rhythmicity in birds remain to be clarified by experimental work. Yet it is clear that of the known factors of the external environment, light alone has been found capable of effecting complete spermatogenesis in birds which reproduce seasonally. If light is so firmly implicated by experimental evidence,