78 THE LIFE OF THE PLANT 



mediate results of the respiration which awakens plants 

 to life. 



Respiration as such explains the continual loss of 

 dry matter, the fact which called our attention to the 

 relation of the seed to the air. Respiration is a slow 

 and continual combustion of the carbon and hydrogen 

 of an organic substance, and as a matter of fact if 

 we compare the analysis of a seed with that of the seed- 

 ling which has grown out of it, the decrease in dry 

 weight has to be put down precisely to those elements, 

 whereas the quantity of nitrogen shows no change. 



Having proved that a process of respiration takes 

 place in the germinating seed similar to that in the 

 animal organism, we may now go a step further and ask : 

 is not this process followed in the vegetable organism 

 by the same results as in the case of the animal organism ? 

 Respiration, being as a matter of fact slow combustion, 

 keeps up the temperature of the animal, warms it ; 

 will it not warm in the same way a young germinating 

 plant, providing it with the heat necessary for its 

 development ? This question brings us to the considera- 

 tion of the third of the three conditions on which 

 germination depends, i.e. to the consideration of the 

 effects of heat. 



Even without exact experiment we notice by general 

 observation that seeds become perceptibly warmer 

 during germination, evidently owing to respiration. 

 Long ago it was noticed that during the malting process 

 the heaps of germinating barley grain get so warm that 

 the rise in temperature can be detected without a 

 thermometer, simply by plunging one's hand into them. 

 It has been noticed also that rotten seeds spontaneously 

 burn, although here to normal vital processes there are 

 added processes of decay which are due to the activity 

 of certain micro-organisms. In more exact experiments, 



