DEPARTMENT OF EXPERIMENTAL EVOLUTION * 



C. B. Davenport, Director. 



GENERAL STATEMENT OF RESULTS. 



The progress in the year ending October i, 1910, made by this Department 

 in the subject under its charge may be considered under seven heads: origin 

 of characteristics, their chemical basis, ontogenesis, transmission, modifica- 

 tion by environment, relations, and the application of heredity to man. 



the: origin of characteristics. 



While the breeder can as yet rarely induce at will a wholly new character- 

 istic by experimental methods, yet in breeding large numbers of individuals 

 new characteristics are occasionally found the proper breeding of which may 

 result in a distinct strain. Thus, among the 17,000 pedigreed poultry bred 

 by us such characteristics have appeared — at first hardly noticeable, but in 

 the past few years becoming well marked and even striking. Among such 

 are toes without nails ; toes with double nails ; extra tubercles on the side of 

 the single comb which have given rise to a row of such tubercles in later 

 generations ; large depressions on the ridge of the beak (associated with an 

 imperfect development of the nasal bone) ; and a horn on the ridge of the 

 beak. Among plants, likewise, such characteristics have occurred, if not 

 absolutely unparalleled, at least new to the species under consideration ; such 

 as aecidia or cup-shaped foldings of leaves, "quilling" of the lappets of com- 

 positae, triple cotyledons, fasciations. We are not yet able to induce these 

 at will in any strain, but have developed strains in which some of these con- 

 ditions are normal. 



The origin of spots on the wing-covers of lady-beetles has been particularly 

 considered by Mr. Johnson, in his publication on that group, and he concludes 

 that the evolution of any changes inside of species is chiefly the loss or the 

 confluence of spots. The differences are often of a qualitative order. 



THE chemical basis OE CHARACTERISTICS. 



Substantial advance has been made in this subject during the current year 

 in consequence of the appointment of Dr. Gortner and the equipment of 

 a chemical laboratory. In the first place, fundamental defects in current 

 methods of isolating the black pigment of hair, wool, and feathers were dis- 

 covered. With the improved method the assertion that dominant white has 

 a hyperoxidized black pigment was shown to be incorrect. In neither domi- 

 nant nor recessive white is pigment formed; the additional factor in the 

 dominant type is suspected to be an anti-enzyme. 



* Situated at Cold Spring Harbor, Long Island, N. Y. Grant No. 601. $30,970 for 

 investigations and maintenance during 1910. (For previous reports see Year Books 

 Nos. 3-8.) 



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