The Kinds of Work That Are Done by Plants 91 



primarily to give only light incidentally give much heat as well. 

 But it is this very same heat developed and kept in regulation 

 which is the basis of the uniform warmth of the animal body. 

 A few pages earlier it was shown that the carbon in the carbon 

 dioxide released in respiration comes from inside the plant. This 

 being so, respiration ought always to entail a loss of weight in 



Fig. 31. — Plants of Buckwheat grown from the same number and weight of seed in h'ght 

 and darkness respectively. The plants are in porous saucers supplied with water and 

 minerals from below.- 



respiring plants or animals; which in fact is found by experiment 

 to be true. The loss must be compensated by new supplies of 

 food, else the phenomena of starvation, including emaciation, 

 ensue. The emaciation of a starved animal, indeed, is due much 

 more to the loss of substance through respiration than through 

 the ordinary excretions. In plants, however, it often happens 

 that those which have lost much weight by respiration without 

 opportunity to make it up by photosynthesis, look larger than 



