26 THE GERM THEORY OF DISEASE. 



antagonized by the acid juices it meets there and its molecular 

 movement destroyed. 



If, however, the noxious element be acid in its reaction, 

 the juices of the stomach do not interfere with its molecular 

 movement, but rather favor it. And instead of being de- 

 stroyed, it is rendered even more virulent. This action of 

 the stomach, he argues, is a very positive proof of the chemical 

 nature of these poisons. 



It is a noteworthy fact that in this essay Prof. Liebig 

 practically ignores the microscopic demonstrations of the yeast 

 plant. He evidently regarded it as, to a large extent, a fiction 

 of the brain of over-zealous investigators, using what was 

 in that day considered very high powers of the microscope. 

 Not believing in the existence of the yeast plant, or the 

 organisms of disease, he says, "The vital principle is only 

 known to us through the peculiar forms of its instruments; 

 that is, through the organs in which it resides. Hence, what- 

 ever kind of energy a substance may possess, it is amorphous 

 and destitute of organs from which the impulse, motion or 

 change proceeds ; it does not live." 



The basis which he gives for the proof of the existence of 

 life stands to-day in its full power. And if he is at last 

 beaten in the argument, it is because facts have been brought 

 forward and proven by incontrovertible observation that will 

 satisfy this basis. This basis is contained, practically, in one 

 sentence, which I quote: "Our notion of life involves some- 

 thing more than mere reproduction, namely, the idea of an 

 active power exercised by virtue of a definite form, and pro- 

 duction and generation in a definite form." 



