234 CACAO TREES, SAGO PALMS, ETC. 



would, however, probably show a very much higher 

 temperature. Yet cool fruits will grow on what is 

 practically dry and super-heated sand and do so in the 

 desert zone. 



On the other hand, the increased temperatures main- 

 tained by plants above that of the atmosphere, during 

 the bitter chill of a winter's night, in cold climates, 

 seems to be due to their power of closing their pores 

 at night, under the influence of great cold: thus 

 mechanically arresting the process of evaporation, by 

 which their juices would be cooled. All this, however, 

 opens up a very large and very wonderful branch of 

 enquiry, into which it would be impossible for us to 

 enter, further than to remark that it seems to be 

 a species of counterpart to the faculty possessed by 

 animals, of maintaining the temperature of their bodies 

 at their normal point, or nearly so, under the most 

 extreme variations of climate. This in the case of the 

 human subject is ascertained to be slightly over 98^ 

 Fahr., and it is impossible for it to vary more than two 

 or three degrees either way for more than a very brief 

 period of time without serious disturbance of the general 

 health, and danger, especially in the case of a lowered 

 temperature, even to life itself. Excessive temper" 

 atures are, as we know, kept down, and reduced, by 

 increased transpiration, just as in the case of fruits, 

 which we have been here considering; so again, a 

 diminished action of the skin is one of the effects of 

 cold upon the human frame, exactly as it is in the 

 case of trees and plants. 



The more we examine this subject, in fact, the more 

 we shall find how closely many of the most important 

 functions of plants and animals are allied to each other. 



