DEPARTMENT OF EXPERIMENTAL EVOEUTION. 9I 



Noteworthy are the grand period of maximum egg-laying from the middle 

 of March to the middle of May and the period of depression from July i to 

 January 15. The fluctuations in the latter period are due chiefly to feeding, 

 as a diet of meat after prolonged abstinence will quickly double, at almost any 

 time, the egg-yield ; but on the withdrawal of such stimulating food the egg- 

 yield rapidly diminishes. Another factor contributing to the irregularity of 

 the egg-yield is the removal for market during June and July of about half 

 the laying hens, and the increase in the number of laying birds during Jan- 

 uary and February by the maturing of the young stock. 



The entire laying plant was removed during December and January a dis- 

 tance of about a mile, to a farm on the plateau, where the conditions are much 

 better for the health of the hens. Artificial incubation and brooding w^ere 

 carried on at the laboratory and its immediate vicinity. In addition to poul- 

 try some guinea-fowl w^ere bred. 



Finches. — Sixty pairs of breeding canaries were mated and 5 of other 

 finches. A total of 329 birds hatched, but owing, probably, to inadequate heat- 

 ing facilities only about 100 birds were reared. This number includes 3 

 hybrids between gray and white Java sparrows, which show gray dominant. 

 During the year our stock of canaries was increased by the importation of 

 some of the more novel and at the same time expensive varieties. Owing, 

 perhaps, to incomplete acclimatization these have bred poorly this season. 



Sheep and Goats. — Eight sheep and 9 goats were born during the year; in 

 both species white fleece is dominant over black, but not over red. As a pure 

 white Angora goat was used as sire during the present season only white or 

 white-and-red kids were born. The neck "wattles" are dominant over their 

 absence. During the year w^e received from Dr. A. G. Bell, a black ram with 

 6 nipples, which will be used in place of our former ram to prevent too close 

 inbreeding. No increase in the number of nipples beyond 6 has yet occurred. 



Cats. — The limitations of room have caused this experiment to come to a 

 partial standstill. It is planned to provide improved and enlarged quarters 

 for it. Some 20 cats were born during the year. 



Drosophila. — The study by Dr. F. E. Lutz of the inheritance of the abnor- 

 mal venation of the fruit-fly has been continued through more than 40 gener- 

 ations. The results will be ready for publication shortly. The inheritance 

 of the scalloped wing was also tested and the inheritance of dwarfness. If 

 time permits this latter work will be continued and the effect of environment 

 will be considered. However, special stress will be laid during the coming 

 year upon the work with Gryllus. 



Gryllus. — The inheritance work with this genus has been continued along 

 the lines laid down four years ago. While Dr. Lutz has been chiefly con- 

 cerned with the wing dimorphism, data have been secured concerning all of 

 the important organs. About 2,000 pedigreed offspring have been obtained 

 this season. In JMay Dr. Lutz made a short trip to Cuba and Mexico with 



