proceedings: botanical society of WASHINGTON 1 45 



sary in these States, in order promptly to locate scattered infections 

 which may occur, it is believed that further seriously destructive out- 

 breaks of canker can be prevented. 



The 1 8th annual meeting of the Society was held immediately after 

 the regular meeting. In the absence of the regular officers, all reports 

 were omitted. The following officers were elected for the ensuing 

 year: President, Karl F. KellERMan; Vice-President, C. R. Ball; 

 Recording Secretary, Chas. E. Chambliss; Corresponding Secretary, 

 R. K. Beattie; Treasurer, h. L. Harter. Walter T. Swingle was 

 nominated for Vice-President in the Washington Academy of Sciences. 



The 131st regular meeting of the Society was held in the Assembly 

 Hall of the Carnegie Institution at 8 p.m., Thursday, December 5, 

 1918.^ Forty -four members and three guests were present. The 

 following papers were presented: 



Effect of temperature and other meteorological factors on the growth of 

 sorghums: H. N. Vinall. The speaker stated that the purpose of tliis 

 study was to determine the reactions of the sorghum plant to climatic 

 conditions. Several varieties were grown under field conditions at 

 Chillicothe, Texas, Bard and Chula Vista, California, and Puyallup, 

 Washington. The average of the monthly means of temperature for 

 the growing seasons at the above points was 75.6°, 81.8°, 62.4°, 

 and 60.4° F., respectively. The percentage of actual to possible sun- 

 shine was 75, 93, 68, and 46. The total degrees of positive tempera- 

 ture received by the sorghums at Chillicothe was 3028°, at Bard 4236°, 

 at Chula Vista 1895°, and at Puyallup 1615° F. 



None of the sorghums matured at Puyallup, but all matured at Chula 

 Vista with only 280° difference in the total of positive temperatures. 

 This would seem to indicate that the amount of sunshine is an impor- 

 tant factor in bringing sorghums to maturity. The conformance of the 

 sorghums of Chillicothe, Bard, and Chula \^ista to Linsser's Law of 

 Growth was remarkable. The "physiological constant," according to 

 this law, for the period from planting to maturity, was for Chillicothe 

 0.539, Bard 0.530, and Chula Vista 0.526. 



Vegetative characters which are ordinarily considered stable, 

 such as the number of leaves per plant, varied with the climatic condi- 

 tions. Blackhull kalir had 3 and Sumac sorgo 6 more leaves at Bard 

 than at Chula Vista. The varieties also showed decided differences in 

 height and diameter of the stem and in the size of the leaf at these 

 two places. 



Studies on the effects of different dates of planting at Bard indicate 

 that "more favorable conditions are obtained if the date of planting 

 is regulated so that the early stages of the plant's development coincide 

 with a period of high temperatures and the later stages, when the plant 

 is nearing maturity, come when moderate temperatures prevail." 



' The November meeting was not held on account of the influenza epidemic. 



