HEAT AND MOISTURE. 21 



SECT. III. 



ON HEAT AND MOISTURE. 



The essential agents in the production and 

 continuance of this tribe of plants are heat and 

 MOISTURE^ for there is no place where they 

 abound more than where it is hot, and damp 

 almost to saturation ; they are here found in vast 

 quantities, but still there are some that will thrive 

 in a comparatively low temperature (50° or 55°), 

 and with a judicious application of moisture attain 

 a robust habit. Such plants are mostly from 

 elevated districts, and consequently the tempera- 

 ture is much lower. Of the two necessary agents 

 mentioned, moisture certainly exhibits the greatest 

 effect upon plants, and in its proper appliance 

 and withholding, rests the entire art of their cul- 

 tivation. 



In this particular these plants exhibit a most 

 decided difference to any other cultivated tribe, 

 for they will bear an increase or diminution 

 of temperature better than an ill-timed altera- 

 tion of the supply of moisture, yet it is at the 

 present time considered, by some cultivators, 

 that they will not flower so fine, unless they are 



