34 



■ 



coulci probably be prevented if inspectors and field workers could 

 only be supplied with, more knowledge as to the nature and causes 

 of the diseases to which the spoilage is chiefly due. It is hoped 

 that the investigation necessary to supply this knowledge can be 

 established at the Botanic Garden in the near future on a perma- 

 nent foundation, commensurate with the extent of the need and 

 the Importance of the work. 



RESUME OF 1920 

 Investigations 



^ 



Plant Breeding. — Investigations of the laws of heredity and 



I 



variation in plants have been carried on as heretofore by the 

 curator of plant breeding, wuth the full-time aid of one as- 



sistant, since 



July 



I. 



These have led to the discovery and 



isolation of several new genetic factors in garden peas, par- 

 ticularly one which distinguishes narrow scimitar podded varie- 

 ties from the ordinary types with wide, straight or but slightly 



curved pods. One new seed-coat color pattern 





tripin 



O' 



ha 



been discovered, and studies so far made indicate that at least 

 two genetic factors are involved in its heredity. Studies on in- 

 heritance of purple pod, yellow pod, and green pod color have 

 thrown sohie new light on the genetic relations of these charac- 

 ters and their genetic factors. Studies on inheritance of height 

 in peas, covering a large number of varieties, indicate that a very 

 complex genetic basis is involved. Several new factors for 



height have been isolated. The main studies on linkage among 

 the genetic factors of peas are progressing satisfactorily, al- 

 though still hampered by lack of adequate facilities in the way 

 of trained assistance, satisfactor}^ land for pea cultures, green- 

 house space, and a calculating machine. Investigations on gar- 

 den peas by plant-breeders all over the world have resulted in 

 isolating and working out the inheritance to date of over eighty 

 hereditary characters. Genetic studies of corn and castor beans 



have been 



given up 



here because of lack of facilities. Tvliss 



i\Ieyer has rendered valuable assistance from the time of her 

 appointment as part-time assistant in the spring. Since July I, 

 her whole time has been devoted to plant-breeding work. 



