76 re;ports oi' investigations and projects. 



DEPARTMENT OF EXPERIMENTAL EVOLUTION * 



C. B. Davenport, Director. 



The work of the Department during the past year has continued along lines 

 already laid down in previous reports. The direction that our work has 

 already taken has been determined by the conviction that the most important 

 definite question to answer is : How may the course of the stream of germ 

 plasm that has come down to us from remote ages be controlled in its onward 

 course ? This has led us to start a certain number of strains with the inten- 

 tion of controlling their onward progress, first by controlling all matings, 

 and, secondly, by controlling or at least observing the environmental condi- 

 tions. The number of these controlled strains now at the Station amounts 

 to several hundred, of which 20 are in mammals, 60 in poultry, 15 in cage- 

 birds, about 5 in crickets, 6 in the fly Drosophila, 5 in Crioceris, a dozen 

 other strains in insects, and over 400 in flowering plants. In som.e cases the 

 controlled strains extend back for four years, and in the case of rapidly 

 breeding flies for 20 generations. While in most cases the strains have been 

 subject to varying environmental conditions resembling those met with by 

 the wild species, in a few cases we have attempted to control certain factors 

 of the environment, particularly temperature. Such then, in broad outlines, 

 is our work — a work that necessarily demands much time for results. Nature 

 is in no hurry, and for most animals and plants it takes a year to make a 

 single onward step. The administrative work referred to at the end of this 

 report is all directed toward the maintenance and the study of these strains 

 and the study of their environmental conditions. 



REPORTS ON SCIENTIFIC WORK. 



Heredity in Poultry. — C. B. Davenport. 



In the work with poultry 55 of the strains of 1906 were continued and 5 

 new ones started. Approximately 15,000 eggs of known parentage were 

 incubated and 3,618 chicks hatched. Some of the subjects upon which the 

 breeding experiments in progress are expected to throw light are : 



( 1 ) The inheritance of abnormalities, such as cerebral hernia, polydactyl- 



ism, syndactylism, winglessness, taillessness, etc. 



(2) The inheritance of fluctuating variability; increase of red in plumage, 



of split in comb, of nostril height, of egg-laying; decrease of 

 comb ; increased length of tail. 



(3) The inheritance of strong versus weak characters, as in poly dactyl- 



ism. 



(4) The inheritance of special plumage marking, such as barring, span- 



gling, mottling, and blue. 



(5) Inheritance in hybridization of localized pigment pattern. 



(6) The analysis of the components of the fowl's comb. 



* Situated at Cold Spring Harbor, Long Island, New York. Grant No. 397. $25,000 

 for investigations and maintenance. (For previous reports see Year Book No. 3, pp. 

 23-32; Year Book No. 4, pp. 87-107, and Year Book No. 5, pp. 92-105.) 



