DEPARTMENT OF EXPERIMENTAL EVOLUTION * 



C. B. Davenport, Director. 

 GENERAL STATEMENT OF RESULTS. 



The principal developments of the year are (i) the initiation, at Cold 

 Spring Harbor, in cooperation with this Department, of the Eugenics Record 

 Office for the study of human heredity and the application of the laws of 

 heredity to human affairs; (2) the discovery of the method of heredity of 

 epilepsy in man, with clear indications of how it is reproduced and how its 

 recurrence in later generations may be prevented; (3) the termination of 

 Dr. Shull's work at Santa Rosa and the approach to completion of his book 

 on Burbank's work ; (4) the publication of Dr. Harris's statistical compari- 

 son of the fruits of Staphylea that develop with those that fail, showing the 

 much greater symmetry of the former; (5) the publication of the researches 

 of Dr. Frank E. Lutz, who bred fruit-flies for 43 generations, secured varia- 

 tions in the wing venation unlike anything known in nature in the group of 

 Diptera (flies), found that despite long disuse of wing in these flies there 

 was no evidence that this disuse affects their size, and discovered that when 

 the flies are allowed to choose they tend to select normal consorts; (6) the 

 discovery of two types of melanin and a clearer definition of the pigment- 

 forming processes; (7) the publication of the demonstration by Castle in 

 guinea-pigs and by myself in fowl of Guthrie's error in concluding that the 

 germ-plasm is affected by the soma. 



DETAILED REPORTS ON SCIENTIFIC WORK. 



HEREDITY IN POULTRY, 



Rumplessness. — Progress was made during the year in perfecting two 

 strains of rumpless (tailless) fowl. These have been continued, not only to 

 demonstrate their purity, but also to furnish material for the study that was 

 begun last year by Miss Elizabeth S. Lum and continued by her during six 

 weeks of the present summer. The study of the caudal vertebrae in a series 

 of fowl, both with and without a uropygium, reveals a striking variation in 

 their number. But in the rumpless fowl the number is invariably much 

 smaller than in the tailed form and the bones are more or less fused together. 

 The whole circulation and innervation of the region is rudimentary. 



Control of the Form of Characters hy Sex. — A special quantitative study 

 is being made of various organs, such as the Y-comb and booting, to deter- 



* Situated at Cold Spring Harbor, Long Island, N. Y. Grant No. 676. $33,734 for 

 investigations and maintenance during 1911. (For previous reports see Year Books 

 Nos. 3-9.) 



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