With respect to the American “corn belt” in general, it is not certain how far the rules deduced for Ohio are applicable. Professor Smith has been inclined to look upon July rainfall as the dominating factor for the whole of that region; so that, for example, a difference of 1 inch in the rainfall (viz., a total for July of 4.4 inches or more, as compared with 3.4 inches or less) has been held responsible for an increase of 500,000,000 bushels of corn in the eight principal corn-growing States. It has also been stated that in the four States of Indiana, Illinois, Iowa and Missouri an increase of half an inch of rain in July meant an increase of $150,000,000 in the value of the crop. These figures have, however, been challenged, and the subject is still under discussion. The study of the critical periods of different crops, and the determination of the amounts of heat and moisture most favorable to the success of the crop at such periods, may be regarded as the leading task of the agricultural meteorologist. The most elaborate researches of this character have been made in Russia by Professor P. Brounov, who founded in 1896 a meteorological bureau, attached to the Ministry of Agriculture, with an extensive network of stations scattered over the Russian Empire. This bureau was quite distinct from the ordinary meteorological service, under the direction of the Central Physical Observatory in St. Petersburg. Just before the war Professor Brounov had 150 stations in operation; most of them for observing the effects of weather on the leading cereal crops, though some studied the corresponding relations of horticulture or the animal industries. Each agricultural station comprised a small plot of land, on which a certain sequence of crops was grown year after year under conditions of cultivation as nearly uniform as possible, the only variable factor being the weather. Meteorological instruments were installed in the immediate proximity of the plants under investigation. Prior to 1914 Brounov had determined the critical periods of most of the crops grown in Russia, and had published a great deal of information on this subject that could be turned to practical account by Russian farmers.