16 EXPERIMENT STATION RECORD. [Vol. 41 



in surface, being greatest with tlie first increase in surface and declining witli 

 subsequent increases. 



Climate formula and reduced rainfall, W. Koppen {Met. Ztschr. [Bruns- 

 icick], 36 {191'J), Xo. 1-2. pp. i-7).— Tlie autlior explains a formula wbich is 

 proposed as a convenient method of briefly designating the climate of a par- 

 ticular place. 



The bioclimatic law as applied to entomological research and farm prac- 

 tice, A. D. Hopkins {8oi. Mo., 8 {1919), No. 6i pp. 496-513, figs. 3).— This law, 

 as explained in an article previously noted (E. S. R., 39, p. 317), is defined and 

 certain of its applications discussed. 



It is stated that "we have in the so-called bioclimatic law of latitude, longi- 

 tude, and altitude an example of a natural law which represents the general 

 laws of climate as affecting the seasonal activities and geographical distribution 

 of land-inhabiting species of plants and animals, periodical practice in agricul- 

 ture, and the adaptation of farm crops to the requirements of cUmatic condi- 

 tions. The law is founded on the determined country-wide average rate of 

 variation in the time at which periodical events occur in the seasonal develop- 

 ment and habits of plants and animals at different geographical positions 

 within the range of their distribution. Other things being equal, this varia- 

 tion is at the rate of four days for each degree of latitude, 5° of longitude, and 

 400 ft. of altitude." Isophanal maps of the United States, constructed on this 

 basis, are shown and discussed. 



It is claimed that having "the date of a periodical event or practice at an 

 established base in any given season we can, by means of the time constants 

 of the law and their equivalents in latitude, longitude, and altitude, compute 

 a corresponding date constant of the same event for any other place within 

 the range of the species or periodical practice involved. Or, having deter- 

 mined for any section of the country the upper or northern limit in the 

 geographical distribution of a native or introduced species or variety of animal 

 or plant, the corresponding limit constants for altitude or latitude can be com- 

 puted for any other section ; and having determined also the lower or southern 

 limit, the altitude and latitude constants can be worked out for the possible 

 geographical range in which the species or variety, under its other environ- 

 mental requirements, would survive and thrive." 



The applications of the law to entomological research are illustrated in the 

 cases of the southern pine bettle, the western pine beetle, the mountain pine 

 beetle, the pine bark louse, the hatching of Chermes on Pike's Peak, and the 

 Hessian fly. 



Among the problems in farm practice which have a direct relation to the 

 bioclimatic law, the following are briefly discussed: "(1) Seedtime and har- 

 vest, as applied to a wide range of farm, garden, and truck crops, and as 

 adapted to the varying climatic conditions which prevail from the lowest to 

 the highest latitudes and altitudes and from eastern to western longitudes of 

 the United States, (2) the application of remedies against insect pests and 

 plant and animal diseases, [and] (3) the selection of varieties of domestic 

 animals and cultivated plants and the types of agriculture best adapted to 

 regional and local conditions of soil, climate, etc." 



A soil temperature survey of the United States and Canada {Set. Amer., 

 120 {1919), Xo. 19, p. 4S1). — It is announced that a committee of the Ecological 

 Society of America has organized a soil temperature survey of the United 

 States and Canada. 



"The present plan is to carry on observations at various places for a num- 

 ber of years under identical conditiona Upwards of SO stations are now in 



