REPORT OF THE PRESIDENT, 1913. 17 



Professor B. E. Livingston, formerly a member of the departmental 

 staff, on the water relations of plants; to the determinations of auto- 

 nomic movements in opuntias by Mrs. Shreve, whose volume on ''The 

 daily march of transpiration in a desert perennial" is in press as 

 publication No. 194; to the investigation of Professor H. M. Richards 

 on the acidity, the gaseous interchange, and the respiration of cacti; 

 to the surprising properties of the opuntias in fruit development, 

 brought to light by Professor D. S. Johnson; and to the favorably pro- 

 gressing enterprise undertaken by the department, in collaboration 

 with Dr. N. L. Britton and Dr. J. N. Rose, for a systematic determi- 

 nation of the distribution and relationships of the cactus family of 

 plants. 



The work of the year in this department records, among many 

 other advances, additional contributions to the laws of human inheri- 



De artmentof *^^^®j *^^ rcsults of further and more conclusive 

 Experimental studics of the transmission of traits in plants of the 

 Evo ution. genera Bursa and Oenothera; and some preliminary 

 indications of specially instructive investigations in the field of bio- 

 chemistry. The Director has divided his time between researches 

 based on breeding experiments carried on at his station and studies 

 of data bearing on human heredity collected under the auspices of 

 the Eugenics Record Office, of which he is also the directing head. 

 In addition to the researches carried on by Doctors Banta, Gortner, 

 Harris, and Shull of the resident staff. Dr. A. F. Blakeslee, Dr. G. C. 

 Bassett, and Professor John H. Gerould have pursued investigations 

 in collaboration with this staff. One of the most important of these 

 cooperative enterprises is the joint investigation of Dr. Blakeslee 

 and Dr. Gortner on the low organisms called mucors, from which it 

 appears that sex-differentiation in these organisms has a determinate 

 physical basis. This conclusion appears to bear a close relation to 

 similar fundamental conclusions reached independently in other lines 

 of work by our Research Associates, Dr. Reichert and Dr. Osborne. 



The exigencies of his experimental work going forward at the 

 departmental station have prevented Dr. Shull from completing the 

 manuscript of his account of the work of Luther Burbank. It has 

 been arranged, therefore, that he shall spend some months abroad, 

 beginning with October, 1913, in order that uninterrupted attention 

 to this manuscript may enable him to finish it without undue delay. 

 The importance of the biochemical laboratory, in charge of Dr. 

 Gortner in connection with the department, has been well attested 

 during the year by the aid he has rendered in the complex studies 



