REPORT OF THE SECRETARY 129 



Shannon trail just beyond No. 2, and this colony was kept on record 

 until just before departure on June 15 — about 125 days in all. A 

 colony of E. hamatum, found a few days later, was on record for nearly 

 as long. Approximately 50 other colonies of these 2 species were 

 studied more or less intensively during the 4 months. 



"The findings, first of all, showed in convincing ways that the 

 periodic behavior changes (regular alternation of nomadic and 

 statary — i. e., sessile — colony behavior) that I have found invariable 

 for these ants in the rainy season also hold through the dry season. 

 Regular phases were found as follows : For E. hamat'mn^ about 17 days 

 nomadic and about 20 days statary in alternation; for E. iurcheUi, 

 about 12 days nomadic and 21 days statary in alternation. An inten- 

 sive study of colony brood-production, paralleling the behavior studies, 

 revealed that in colonies which survive the dry season with their queens, 

 new broods are produced at very regular intervals as in the rainy sea- 

 son. Further evidence was found that this regular brood-production, 

 based of course upon a very regular delivery of successive batches of 

 eggs by the queen, provides the causal basis for the described regularity 

 of colony behavior. For example, the queens of E. hamatum produce 

 new batches of eggs at about 36-day intervals. This island study of 

 1946 shows that this remarkable performance ordinarily is continuous 

 throughout the year. 



"The production of male individuals, it was found, occurs in the dry 

 season, at times characteristic of the species. Evidently in colonies 

 that produce males, only one brood of males per season is produced, 

 otherwise the broods are immense worker broods as in the rainy season. 

 The production of males was studied, from early larval stages to ma- 

 turity and dissemination by flight. A brood of (about 3,000, as a rule) 

 winged males requires about 3 weeks for its complete exodus through 

 nightly flights, after emergence. Results indicate that most of the 

 males that survive the flight reach other colonies (evidently through 

 chancing upon and following raiding trails to the bivouacs). The 

 flight evidently operates against adelphogamy, although .some evi- 

 dence was obtained for occasional returns of males into their colonies 

 of origin. From this 1946 work a considerable part of the virtually 

 unknown problem of Eciton mating can be sketched in. More of it. 

 and especially how the wingless queens are produced, we hope to learn 

 in 1947^8, when a project is planned for studying transitional condi- 

 tions in the Ecitons from rainy to dry season months." 



Dr. James B. Hamilton, professor of anatomy. Long Island College 

 of Medicine, and one of the foremost authorities on hormones, initiated 

 a most interesting and promising line of research dealing with the 

 matter of baldness, a subject on which he has already published im- 

 portant papers. His experimental approach was through the three- 



