Ixviii Department of Plant-Breeding , 



interesting results liave already been obtained and are being tested as 

 rapidly as possible. 



Studies on variation. — In starting the work of this Department in 1907, 

 it was conceived that the most important problem in the field of breeding 

 was to determine what factors influence variations and what can be done 

 to force variations in plants. Variation is important in the starting of any 

 breeding work ; in fact, no advance can be made without variation. With 

 this in mind a great deal of work has been conducted in the Department 

 in order to obtain further knowledge on the subject of the production of 

 variation. 



The special problems which are being studied under this general head- 

 ing were seated in previous reports and need not be announced here. 



Some experiments to test the so-called Knight's Law, that high feeding 

 increases the range of variation, were conducted by Dr. H. H. Love and 

 have been published in Bulletin 297. A similar series of experiments are 

 being conducted by Dr. C. H. Myers and a part of these results will be 

 published within the coming year. 



Some very interesting experiments to determine the efTect of tempera- 

 ture changes in producing variation have been conducted for the past 

 three years by Dr. R. J. Evans and A. W. Drinkard. The material used 

 was Stellaria media and browallias. The results of this work will prob- 

 ably be published during the coming year. 



Another extensive experiment in this same field is a study of the varia- 

 tions in the common oxeye daisy {Chrysanthemum leucanthemum) , con- 

 ducted by Dr. H. H. Love. Here a study of the range and amount of 

 variation in diiTerent habitats and under cultivation is being made. The 

 variation in the same locality in different seasons, and the change in type 

 from the beginning to the end of the blooming season, are other phases 

 of this problem. 



Studies on the hnvs of inheritance. — The studies of hybrids and the 

 segregation and inheritance of characters are being conducted and ex- 

 tended as rapidly as possible. Doctor Gilbert's experiments with hybrid 

 tomatoes and with phlox are practically completed and are being prepared 

 for publication. Particularly interesting results have been obtained in 

 these experiments on the inheritance of size in tomatoes. 



A similar study, which is being conducted on a fairly extensive scale, 

 is in progress with peppers. The pepper furnishes a number of con- 

 trasted characters in its numerous varieties, and affords a fine field for the 

 study of problems of inheritance. Such characters as yellow and red 

 color, erect and reversed fruit, presence or absence of chlorophyll in the 

 young fruit, and presence or absence of pungency, segregate and are 

 inherited in Mendelian proportions. The question of bodily characters, 



