244 PROCEEDINGS OF THE OHIO ACADEMY OF SCIENCE. 



perature is too low for the best growth of plants, as in Alaska, 

 sunshine becomes the most important factor. In fact we must 

 not try to separate sunshine and heat. Solar energy is the factor 

 that enables the plant to make use of the food brought to its 

 roots by moisture, whether we call this energy degrees or 

 calories. 



A value called the "Sunshine-hour degree" has been ob- 

 tained by multiplying the average daily heat necessary to grow 

 and mature a crop by the total possible hours of sunshine from 

 planting to harvesting. We have worked out the sunshine-hour 

 degree for corn in the United States and find that between lati- 

 tudes 30 and 35 it is 80,313; between latitudes 35 and 40 it is 

 65.778, and between latitudes 40 and 45 it is only 47,887. 



This shows that the number of sunshine-hour degrees neces- 

 sary to make a crop diminishes as the latitude increases, and 

 explains why there is a decided difference in the quantity of heat 

 necessary to grow and mature the same crop at different latitudes 

 due to the difference in the quantity of sunlight. 



AGRICULTURAL METEOROLOGY 



Russia has apparently taken the lead in trying to determine 

 the most critical period for field crops, as well as the weather 

 factor most affecting them, by the inauguration of studies in the 

 field. 



The Russian Bureau of Agricultural Meteorology was au- 

 thorized in 1894 and began its observations in 1896. In 191 2 they 

 had observations under way at 81 different experiment stations 

 where meteorological observations were being made as near as 

 possible to the test farms. During each year they have made a 

 detailed study of the effect of the various weather factors upon 

 the development of the plant and the final yield of the crop. 



In Canada Mr. R. M. Mills has been placed in charge of 

 similar work, and during the summer of 191 5 he has had records 

 made relative to the spring wheat crop at 14 different experiment 

 farms scattered from coast to coast. 



Forms were prepared covering 73 different items, among 

 them being the average height of the plants on the plot every 



