DEPARTMENT OE EXPERIMENTAL EVOLUTION. 85 



THE ORIGIN OF CHARACTERISTICS. 



Work on this topic involves the abihty to produce them by changing the 

 physical and chemical environment; but it also includes observing the condi- 

 tions under which they arise "spontaneously" or by mutation. Data con- 

 cerning the origin of characertistics have been acquired in the course of our 

 studies. Several new qualities have arisen; suddenly and de novo from 

 parents of well-known pedigree, such as poultry with short mandibles, comb- 

 less birds, birds lacking one toe on each foot, with two toe-nails to a digit, 

 with no nail, without one or both wings, and without a tail. All of these new 

 characters, excepting two that were not tested, were permanent acquisitions 

 of the germ-plasm. Our associate, Prof. W. L. Tower, has tried, with much 

 success, to control the origin of new characteristics in the Colorado potato- 

 beetle and its allies. His results have been published in his work* "Evolution 

 in Chrysomelid beetles of the Genus Leptinotarsa." In high temperature 

 and dry air the germ-plasm of this beetle produced less pigment ; in other cases 

 it gave rise to an increased number of generations in the reproductive cycle^ 

 and was otherwise modified. For the immediate future we have planned a 

 series of studies on the effect of cave conditions in modifying characteristics, 

 to be in charge of Dr. A. M. Banta, who will become a resident investigator at 

 this Station. 



THE CHEMICAL BASIS OF CHARACTERISTICS. 



In my last report I mentioned the discoveries of chemical differences in the 

 proteins and hemoglobins of closely related species. There are strong theo- 

 retical reasons for believing that differences in the adult are determined by 

 chemical differences in the tgg. These chemical characteristics lie at the 

 bottom of the morphological and physiological characteristics. During the 

 past year we have sought to determine the chemical differences between the 

 dominant white and the recessive white of poultry plumage. Dr. W. J. 

 Gies, of New York City, was interested in the problem and undertook the 

 determination upon pedigreed material supplied from this Station. Dr. Gies 

 has not yet reported fully, but there is reason for suspecting that a chemical 

 difference exists in the feather of the two kinds of whites. 



The number of problems of a chemical nature that have been opened by 

 the breeding work has rendered advisable the appointment of a physiological 

 chemist, and Dr. R. A, Gortner, a recent graduate of the department of 

 physiological chemistry at Columbia University, entered upon this work 

 September i, 1909. 



* W. L. Tower : An investigation of Evolution in Chrysomelid Beetles of the Genus 

 Leptinotarsa. Publication No. 48 of the Carnegie Institution of Washington. 



