482 METEOROLOGY. GROWTH OF PLANTS. 



and then we determine the temperature of the interval which sepa- 

 rates these two extreme epochs in vegetable life. In comparing 

 these data with reference to the same species of plant grown in Eu- 

 rope and America, we arrive at the following curious result, that the 

 number of days that elapse between the commencement of vegeta- 

 tion and the period of ripeness, is by so much the greater as the 

 mean temperature is lower. The duration of the life of the veget;i- 

 ble would be the same, however diiferent the climate, were this tem- 

 perature identical ; it will be longer or it will be shorter as the mean 

 temperature of the cycle itself is lower or higher. In other woid:.;, 

 the duration of the vegetation appears to be in the inverse ratio of 

 the mean temperature ; so that if we multiply the number of days 

 during which a given plant grows in different climates, by the mean 

 temperature of each, we obtain numbers that are very nearly equ'i" 

 This result is not only remarkable in so far as it seems to indicate 

 that upon every parallel of latitude, at all elevations above the level 

 of the sea, the same plant receives in the course of its existence an 

 equal quantity of heat, but it may find its direct application by ena- 

 bling us to foresee the possibility of acclimating a vegetable in a 

 country, the mean temperature of the several months of which is 

 known. 



CULTIVATION OF WHEAT, ALSACE. 



In 1835 we sowed our wheat on the 1st of November; the cold 

 set in shortly after the plant had sprung, and the harvest took place 

 the 16th of July, 1830. The vegetation during the last days of au- 

 tumn is so slow and irregular, that it may be assumed without sensi- 

 ble error, that it really begins in spring, when the frosts are no longer 

 felt; from this period only does it proceed without interruption. For 

 Alsace I regard this period as beginning with the 1st of March. 



The period of the growth was, therefore, 137 days, the mean tem- 

 perature was 3\r F., (3083" F.) 



Tremois wheat, this same year, required 131 days to ripen under 

 a mean temperature of between 60" and 61° F., (7925" F.) 



At Paris, setting out from the 31st of March, wheat generally re- 

 quires 160 davs to attain maturitv, the mean temperature being 

 about 50" F., (8900" F.) 



At Alais the month of February having generally but few days 

 of heat, it may be regarded as the ei)och when the continued vege- 

 tation of autumn-sown wheat commences. The harvest taking 

 place on the •27ih of June, the number of davs which it requires to 

 ripen is 140, the mean temperature being between 57" and 58" F. 

 (8322" F.) 



CULTIVATION OF WHEAT IN AMERICA. 



At Kingston, New York, the wheat is sown in autumn , vegeta- 

 tion suspended through the winter resumes its activity in the begin- 

 ning of April, and the harvest takes place alxuit the 1st of August 

 The crop is therefore growing during about l'J-2 days under the in- 

 fluence of a mean temperature of 03° F. (7680" F.) 



