36 . HOPKINS: BIOCLIMATIC LAW 



State. As an example, and to serve as a guide to the selection 

 of the time to sow wheat at different latitudes and altitudes 

 to avoid damage by the fly, a calendar of dates and altitudes 

 was prepared and issued with the bulletin, to be used in connec- 

 tion with a map of the State. By means of this map -calendar 

 the average safe date for any place could be determined by the 

 farmer. The practical value of this method was recognized, 

 and demonstrated in the greatly lessened loss from Hessian fly 

 damage the following year (1896) and even to the present time. 



Up to the time the bulletin was published and some years 

 later the determination by the writer as to the rates of varia- 

 tion in time with variations in latitude and altitude was entirely 

 independent of the German literature on the subject, yet the 

 conclusions were practically identical with those published many 

 years before. 



Recognizing the broad application of a knowledge of the sug- 

 gested law to science and practice in entomology, general biology, 

 climatology, and agriculture, the writer has given special atten- 

 tion to the subject during the past 24 years, as applied more 

 specifically to forest entomology. 



As a result of these studies new facts and evidence have ac- 

 cumulated which serve to establish a definite interrelation of 

 organisms with climate and geographical position which we have 

 designated as the Bioclimaiic Law. 



The basic principle in the operation of this law is found in 

 the character of the responses of the organisms to the complex 

 elements and factors of its local and immediate environment. 

 In other words, the organism is utilized as the instrument by 

 which the climate of a place and other influences on its activities 

 are determined and the rate of variation in the dates of events 

 and in latitude and altitude limits of distribution is measured. 

 This method of studying the relations between life and climate has 

 the advantage over that based on artificial instruments designed 

 to record temperature, barometric pressure, humidity, sunshine, 

 rain, wind, etc., because the organism not only records the in- 

 fluence of all of these, but that of all other elements, factors, and 

 forces which affect life activity and which no instruments yet 

 invented can record. 



