DEPARTMENT OF EXPERIMENTAL EVOLUTION. 137 



trolling the size of fetal head, width of pelvis, etc., is easier to admit. 

 At all events, the genetic factors involved must be hypostatic in 

 nature, and in this way the likelihood of the lethal RR combination 

 being formed is greater in matings within the race than it is in matings 

 outside of the race, where possibly an entirely different complex 

 would exist. The work is being continued. 



SEX IN MUCORS. 



The work on sexuality of the mucors has been resumed by Dr. 

 Blakeslee and zygospores hitherto unreported have been discovered, 

 as well as a number of new forms. The investigations, however, have 

 not been carried far enough to warrant an extended report. Atten- 

 tion has been called in earlier volumes, especially in Year Book No. 12, 

 to the relative simplicity of vegetative structure in the mucors, their 

 ease of cultivation, and the fact that the two sexes apparently contrib- 

 ute equal masses of protoplasm to the developing offspring. These 

 investigations are especially adapted to biochemical investigation in 

 the problems of sex, and these can properly be made only with the 

 aid of a biochemist. 



THE INHERITANCE OF GERMINAL PECULIARITIES. 

 FLOWERING PLANTS. 



The genetical work on flowering plants has been seriously interrupted 

 by the war. Our gardener, Mr. Billings T. Avery, jr., who had been 

 identified with Dr. Blakeslee's work for many years, both in the Con- 

 necticut Agricultural College and here, died in service in France, and 

 there has been no one else with the detailed knowledge of the strains 

 who has been able to carry them forward with the same success based 

 on knowledge. Since the war, a satisfactory personnel has been built 

 up, and the prospect is good for a large development of this branch of 

 the work. 



The report of this department in Year Book No. 17, for 1918, told 

 on page 114 of Dr. Blakeslee's plans for developing the adzuki bean as a 

 war measure, undertaken at the request of the National Research 

 Council. He secured the cooperation of some other breeding-stations 

 for the development of this species. From our plots over 4 tons of 

 adzuki beans were raised as a by-product of the experiments, and 

 these were sold at a nominal rate to a nearby State hospital. The 

 reports from other experiment stations on the productivity of this 

 species were not especially favorable, due apparently to the relatively 

 new though destructive "mosaic" disease of shelled beans. We have 

 therefore cut down our work with the adzukis for the present and are 

 testing out the different hues to discover, if possible, inunune races 

 before attempting further breeding with them. 



Of the yellow daisies {Rudbeckia) we have plants growing from 

 crosses made by Mr. Avery before he entered the service. The in- 



