128 CARNEGIE INSTITUTION OF WASHINGTON. 



The subject of inducing mutations is being pursued by Dr. E. C. 

 MacDowell, both by the use of alcohol and by constant extreme 

 atmospheric conditions appUed to rats. He has been assisted in part 

 by Mr. J. W. Gowen. Dr. A. M. Banta is also stud3ing the problem of 

 the possible genetic influence of absence of Ught, such as is experienced 

 by cave animals. He has been assisted by Mr. D. C. Warren. 



We are concerned with the processes by which species become ad- 

 justed to the environment. Drs. Harris, Banta, and MacDowell are 

 studying the results and limits of the process of selection. 



^Ve do not lose sight of the fact that heredity is the control or direc- 

 tion of ontogeny and as opportunity permits we wish to continue and 

 extend the studies that Dr. R. A. Gortner and others have initiated 

 here on the biochemical changes accompanying the development of 

 special traits. Drs. Harris and Riddle are doing something in this 

 field, assisted especially by Mr. John V. Lawrence. 



The staff has sustained a great loss in the resignation of Dr. George 

 H. Shull, who has accepted a call to the chair of botany and genetics 

 at Princeton University. Dr. Shull has been a member of the staff 

 from the organization of the Station — over eleven years. By his 

 persistence, thoroughness, clear insight, and single-mindedness in the 

 pursuit of his investigations he quickly attained the first rank of botani- 

 cal students of genetics. It is early to state which of the discoveries 

 made by Shull at this station will come to be regarded as most impor- 

 tant. His colleagues here have been much impressed with his demon- 

 stration of the isolation of the inferior biotypes in maize through 

 inbreeding and the demonstration of the multipUcity of biotypes in a 

 species regarded at one time as unique in its genus — the shepherd's 

 purse. It is probable that a hundred biotypes (elementary species) 

 could be isolated from the shepherd's purse. If this can be done with 

 so constant a form as shepherd's purse, how vast must be the number 

 of biotypes in notoriously variable species hke golden-rod and rag- 

 weed. The idea of biotypes which Shull so greatly developed is bound 

 to revolutionize, in time, our conceptions of zoological and botanical 

 species and, most important of all, man himself. Shull also attacked 

 with courage numerous difficulties that arose in his work — such as 

 abnormal ratios, the amazing intricacies of Oenothera hybrids, and the 

 sex ratios in a partially hermaphrodite plant (Lychnis). While some 

 of these difficulties of ratios were cleared up, and yielded generaHza- 

 tions as to aberrancy due to duphcate, plural, and linked genes, others 

 are still awaiting interpretation. 



The vacancy created by Dr. ShuU's resignation has been filled by the 

 appointment of Professor Albert F. Blakeslee, of Storrs (Connecticut) 

 Agricultural College. Dr. Blakeslee is no stranger to the Depart- 

 ment; he carried on experiments here from October 1912 to June 1913, 

 on mutation and sex in mucors, and, with Dr. Gortner, discovered the 



