284 



The flowering and ripening of winter wheat during 1882 and 1883 

 has been studied on the basis of data from about 500 stations, com- 

 bined with the previous data for 1880 and 1881. 



The mean daily temperature at the time of flowering is for rye 

 13.3° ; but the individual numbers range from 9° to 18° ; similarly for 

 winter wheat the mean is 16.2° and the range from 10° to 21°. The 

 commencement of vegetation for winter wheat is uniformly adopted 

 as December 1. The sums of the mean daily temperatures have been 

 calculated from several points of departure and seem to prove that 

 the lower limit of useful temperatures is very nearly .5° C, so that 

 we can take ()° C. as the point of departure, as has been done by 

 many authors. 



The sums of the mean daily temperatures, less 6° C, rejecting the 

 negative remainders and counting from the 1st of December, are as 

 follows : 



Periods for winter grain. 



Bye. 



From December 1 to flowering . 

 From December 1 to harvest. . . 

 From flowering to tiarvest 



The harvest date for spring barley is shown to depend in 1882 and 

 1883 quite as little on the date of soAving as it did in 1881. 



The retardation due to altitude is as before, four days per 100 

 meters. Adopting the 20th of March as an average date of sowing, 

 the sums of the mean daily temperatures have been considered up to 

 the date of harvest, with different assumptions as to the fundamental 

 temperature. As before, the best result is given when the sums are 

 taken of the excess of the mean daily temperatures above 0° C, and 

 the resulting figure, 984, is seen to be between the two figures for rye 

 and winter wheat. 



In his third memoir Angot (1888) studies the phenomena of 1884 

 and 1885 in combination with the preceding. The same allowance 

 is made for rates of retardation. The relation between the times of 

 leafing, the mean daily temperature at that date, and the maximum 



