DEPARTMENT OF EXPERIMENTAL EVOLUTION. 



127 



introduce for human food and improve by scientific breeding. This 

 Department has been glad that the services of Dr. Blakeslee and his 

 assistants could be offered to the Government for work with this new 

 Japanese bean and the problem has been accepted by the National 

 Research Council as "an emergency war-research problem." It is 

 proposed as rapidly as possible to develop a stock of seed from the most 

 prolific lines and get the beans on the market and in the meantime to 

 combine, if possible, the desirable characters of size and color of seed, 

 yield per acre, and early maturity. Dr. C. V. Piper, Agrostologist of 

 Forage Crops Investigations of the Bureau of Plant Industry, U. S. 

 Department of Agriculture, who has been growing different races of 

 adzuki beans for several years as a possible forage crop, has kindly sent 

 us seed material of desirable races for starting the hybridization work. 

 Much of the hybridization work must be done in the greenhouse in 

 order to gain an additional generation a year. 



Since the last report Dr. Blakeslee has grown approximately the fol- 

 lowing numbers of plants in garden and greenhouse: 



Table 7. 



Dr. Harris has undertaken systematic tests of the productivity of 

 lines of navy beans as Dr. Blakeslee has of the adzuki beans. He is 

 engaged on experiments upon the technique of variety testing, the 

 theorj' of which is in especial need of investigation. 



Tetracotyledonous heans. — In an extensive series of bean seedhngs Dr. 

 Harris has found some with more than the normal number of 2 cotyle- 

 dons, and these have founded 7 lines which yield exclusively abnormal 

 offspring, of which 7,602 were produced in 1915. The abnormalities, 

 which are probably physiologically related, are: more or less fasciated 

 axis; divided axis ; cotyledons varying in number from 2 to 7, 4 being the 

 commonest condition; primordial leaves varying in number from 1 to 

 14, with a mode at 4; foliar ascidia. It appears that the correlation 

 between number of leaves and number of cotyledons in this abnormal 

 series is low, only about 13 per cent. The field studies on the beans are 

 being supplemented by various intensive physiological investigations. 

 Work on the histology of the normal and teratological seedling in rela- 

 tion to the problem of variation correlation and selective death-rate has 

 been begun by Dr. John Y. Pennypacker. 



