1918] METEOROLOGY. 415 



tion with the Tennessee Experiment Station and certain stations of the 

 Weather Bureau of the U. S. Department of Agriculture with soy beans 

 and corn extending over eight years and covering " a territory extending from 

 the Gulf to the Great Lalies and from the Atlantic to the Rocky Mountains. 

 Records were kept of dates of planting, emergence, blooming, and ripening, to- 

 gether with the daily maximum and minimum temperatures and rainfall. 



" It was found that between plantings made at the same date, but at places 

 having different temperature conditions, there was a wide difference in the 

 length of time required for the different stages of growth. A similar difference 

 was found between plantings made at different dates at the same place. These 

 variations were always in the same direction, but different in amount. It 

 appeared that the higher the mean temperature the shorter the time required 

 for the plant to reach a certain stage." 



With the Mammoth Yellow soy bean, for example, the period from planting 

 to blooming was found to vary from 42 to 133 days. The correlation between 

 mean temperature and length of time from planting to blooming with 50 

 plants of this variety was —0.76 with a probable error of ±0.05. The correla- 

 tion " between mean temperature and the length of the period from emergence 

 to blooming of Indian corn at Wauseon, Ohio, gives a coefficient of —0.79, 

 ±0.05." 



A similar study of the correlation of heat intensity and the length of the 

 incubation period of the cattle tick (Margaropus annulatus) at Dallas, Tex., 

 gave a coefficient of —0.93 with a probable error of ±0.013. 



These results indicate that heat intensity is an important factor in determin- 

 ing the time required by the plant to make its growth and that the period of 

 incubation of the cattle tick " is controlled almost entirely by heat intensity. 

 The temperature control of the length of the seed-tick stage is almost as 

 great." 



A plea is made for cooperative work along these lines. 



Climatic records in the trunks of trees, A. E. Douglass (Amer. Forestry, 

 23 (1911), No. 288, pp. 732-735, figs. 3).— The studies of tree rings briefly re- 

 ported in this article are thought to indicate a relationship between tree growth, 

 .ainfall, and sun spot numbers. 



The pleionian cycle of climatic fluctuations, H. Abctowski (Proc. 2. Pan 

 Amer. Sci. Cong., 1915-16, vol. 2, pp. 112-119; Sci. Amer. Sup., 85 {1918), No. 

 2196, pp. 66, 61). — This article deals with studies the essential features of which 

 have already been noted from other sources (E. S. R., 31, p. 717; 32, p. 509). 



A preliminary note on soil moisture and temperature factors in the winter- 

 killing of grain crops, S. C. Salmon {Science, n. ser., 41 {1018), No. 1201, pp. 

 113, 114). — Briefly describing and summarizing the results of a general study 

 at the Kansas Experiment Station of the causes of winterkilling of cereals, 

 it is stated that " the preliminary work indicates that a sandy soil is colder 

 and the survival of plants growing upon it less than on a dry clay or loam 

 soil, and also colder than a wet clay or a wet loam during those seasons when 

 the ground remains unfrozen much of the time. It appears probable that dry 

 sapd is colder during the winter than a wet sand regardless of the character 

 of the season, but a dry clay or silt loam is colder than a wet soil of the same 

 kind only when the ground remains unfrozen." 



Tropical rains: Their duration, frequency, and intensity, O. L. Fassig 

 {Proc. 2. Pan Amer. Sci. Cong., 1915-16, vol. 2, pp. 460-418, figs. 16).— This 

 study has already been noted from another source (E. S. R., 35, p. 619). 



Frost in the United States, W. G. Reed {Proc. 2. Pan Amer. Sci. Cong., 1915- 

 16, vol. 2, pp. 593-631, figs. 13).— Frost data for selected stations in the United 



