86 



PERIODIC PHENOMENA OF VEGETABLE LIFE. 



by the different repartition of warmth where the mean tempera- 

 ture of the year remains the same. For instance, Heiligenblut 

 in the Mollthal, and Innichen in the Pusterthal, are at the same 

 elevation of about 4000 feet ; they have nearly the same mean 

 annual temperature, but the repartition of the temperature in the 

 different seasons is very different, and this difference is plainly 

 indicated, also, in the period of vegetation, as the following com- 

 parative table will show : — 



Similar results, in different degrees, are not unfrequent in 

 the Alps. 



5. Eemarks on the growth of Cerealia at different elevations. — 

 With a greater altitude not only are the periods of vegetation 

 delayed, but the general development and successful growth of 

 Cerealia is very much impeded. 



The number of grains, the size and number of haulms, and the 

 product altogether gradually decrease as we approach the limits of 

 the growth of corn. In order to judge of the amount of this 

 product, we may take either the proportion which the harvest 

 bears to the seed, or the whole quantity harvested from a given 

 surface under the most appropriate treatment. We have often 

 had opportunities of estimating these quantities by a comparison 

 of long continued lists of observations of great cultivators with 

 other more isolated data. 



The produce compared with the seed varies (taking the mean 

 of Wheat, Rye, and Barley) in the high plains at the northern foot 

 of the Alps, and in the deep longitudinal valleys, from sevenfold 



