DEPARTMENT OF EXPERIMENTAL EVOLUTION. 117 



Hochschule. During the summer Mr. H. H. M. Bowman made detailed 

 observations on Dr. Shull's cultures at Cold Spring Harbor. Dr. J. A. 

 Harris spent two months with Mr. Lawrence, assistant, at the Desert 

 Laboratory, Tucson, Arizona, applying the methods of determining 

 osmotic pressure of vegetable saps from the depression of the freezing- 

 point as developed by Dr. Gortner and himself. 



Dr. R. A. Gortner cooperated with Dr. Harris and Dr. Banta and con- 

 tinued his exceedingly interesting work on the chemical changes that 

 accompany individual development. Dr. Gortner received an excel- 

 lent offer of an associate professorship at the University of Minnesota, 

 and the Laboratory has sustained a severe loss in his departure. During 

 the five years of his connection with this Station he issued 37 contri- 

 butions from the laboratory of which he had charge and advanced 

 greatly our knowledge of the chemistry of animal pigments, the pro- 

 cesses of pigmentation, and individual development. 



Dr. A. M. Banta continued his studies on cave organisms and 

 explored, for material, certain caves of Indiana and, in early October 

 1914, the caves of the Schoharie and Cobleskill Valleys in Central New 

 York, known as Howe's Cave, Ball's Cave, and Becker's Cave. Dr. 

 G. C. Bassett, who was a guest of the Laboratory from July 1913 and 

 later was temporarily appointed to continue his work on the effect of 

 alcoholism in rats, has received a call to the University of Pittsburgh. 

 His work will be continued by Dr. E. C. MacDowell. 



In accordance with plans matured last year Dr. Oscar Riddle trans- 

 ferred the Wliitman collection of pigeons and the new stock to this 

 Station in November and he began work here December 1, and his 

 assistant. Miss Spohn, on January 1. His work is to complete the 

 editing of the Whitman manuscripts for publication. Incidentally he 

 is continuing certain researches that are necessary for the full treat- 

 ment of one of the subjects upon which the late Professor C. O.Whitman 

 had begun work. Mr. Charles W. Metz has been appointed to act as 

 cytologist and is making studies on the behavior of chromosomes (the 

 germ-plasm of Weismann) in the vinegar flies, Drosophila—Si genus which 

 assumes particular importance because of its use for experimental breed- 

 ing by Professor T. H. Morgan, of Columbia University, and his pupils. 



REPORTS ON INVESTIGATIONS IN PROGRESS. 



SEX. 



Studies on sex still constitute an important part of the year's work, 

 although Dr. Blakeslee and Dr. Goodale are no longer with us and Dr. 

 Shull's work has, during his absence in Germany, been directed into 

 other lines. The chief work on this subject is that of Dr. Riddle. 



Sexual Differentiation of Pigeon's Eggs, Oscar Riddle. 



Over a year ago Dr. Riddle showed that, in pigeons, which usually 

 lay two eggs at a time, commonly one male and one female, eggs destined 



