STUDIES ON FERMENTATION. 



47 



harbour to different ferments, even in the inmost parts of the 

 organs, when external causes enable such ferments to find their 

 way into those liquids, and that diseases of greater or less 

 gravity result from this cause. On the other hand, it must be 

 admitted that the bodies of animals in a state of health afford 



Fig. o. 

 no means of entrance to these external germs. At the same 

 time, direct experiment alone can convince the mind as to the 

 truth of this latter assertion. Let us take some of the sub- 

 stances that are to be found inside living animals in perfect 

 health, and expose them, in the same condition in which life 

 has formed them, to contact with pure air. 



For this purpose we must provide ourselves with a glass flask, 

 joined to a copper tap by means of an india-rubber tube, as 

 shown in Fig. 5. The two branches of the tap should be about 



Fig. 6. 



