50 Department of Plant-Breeding. 



5. Effects of chemicals injected into the developing buds at or about 

 the time that the reduction division is taking place in the formation of 

 the germ cells. 



6. Tests of violent temperature changes applied about the time that 

 the reduction division is taking place in the formation of the germ cells, 

 or at other susceptible periods. 



In none of the above cases have the investigations reached conclusion 

 but important results have in some cases been obtained. 



One of the lines of investigation of the above nature has been con- 

 ducted on a somewhat extensive scale by Dr. E. P. Humbert, an assistant 

 in this department. This experiment consists in testing the effect ot 

 chemical injections on pure-bred plants of one of the wild silenes 

 {Silene noctiflora). Coupled with the study of the injected material, a 

 study was also made of the variations which may be derived from pure 

 strains. This was accompanied also by a study of bud variation to 

 determine whether plants from the different seed capsules on the same 

 parent plant will be of the same general type. Something over 15,000 

 plants were grown in connection with this experiment. The paper on this 

 experiment is in press and will soon appear. 



Accompanying the investigation on the causes of variation, studies 

 are being made also on the extent of variation in many plants as found 

 growing in nature and in cultivation. An extended investigation has 

 been made by Dr. C. F. Clark on the range of variation in timothy, the 

 observations being made in connection with the timothy breeding experi- 

 ments outlined above. On a very large number of the timothy plants 

 which have been grown continuously for a number of years, careful 

 notes have been made each year on the date of bloom, duration of bloom, 

 height of plant, yield, etc., and the same notes have been taken continu- 

 ously on the same plants for three to five generations. Comparison has 

 also been made of such characters as yield, and height of plant, one 

 year with another. This was done in order to determine whether plants 

 that give a high yield one year will be the high yielders another year. If 

 this is true, then it would be possible to judge timothy plants as to their 

 value the first year of their growth rather than to wait three years as is 

 commonly felt to be necessary for timothy to reach its maximum growth. 

 This data has been brought together and published as Bulletin No. 279 

 of this Station. 



Another extensive experiment in this line is being conducted by Dr. H. 

 H. Love. In this experiment an attempt is being made to isolate the many 

 types of the common daisy {Chrysanthemum leucanthemum) to deter- 

 mine to what extent they may breed true and thus form the basis of 

 different races. 



