HEAT AND MOISTURE. 23 



Moisture and heat, to a great extent, act 

 and react upon each other, and though the vary- 

 ing positions of the sun, and the length of the 

 days and nights, are a sort of general principle, 

 here obeying the lav/ which we would deduce 

 from the latitude, yet we must be regulated by 

 local causes; for instance, in tropical climates the 

 humidity, and its opposite, are divided into alter- 

 nating periods, and the greater heat falls upon the 

 latter part of the dry period, and the beginning 

 of the rainy period. 



Hence the principal part of the growing and 

 flowering falls upon the period of the rains, and 

 partially upon the dry period or season, for too 

 much humidity while plants are flowering is 

 unfavorable to them ; the season of flowering is 

 various, as some produce them before resting, 

 while others do so immediately afterwards. 



