FUNGUS GERM THEORY. 



country, and there are probably few substances in or 

 upon the earth which are entirely free from them. If 

 their introduction alone is sufficient to produce disease, 

 one malady ought to follow another, until the cata- 

 logue of contagious diseases becomes exhausted, or 

 the organism is destroyed. But many fungi even 

 form articles of diet and medicine, and many animals 

 devour whole forests of living, growing fungi in every 

 mouthful of food they take. Of these not a few 

 are destroyed by the fluids poured into the alimentary 

 canal, digested, and the products appropriated by the 

 organism. The animal, in fact, lives upon them, in- 

 stead of the fungi living upon him ; and in various 

 cases in which certain fungi do actually invade our 

 tissues, the evidence of change in these last having 

 occurred prior to the development of the fungi, is 

 sometimes so distinct, that the conclusion is irresistible, 

 that, so far from the fungus attacking a healthy struc- 

 ture and damaging it, the structure itself had dete- 

 riorated and changed, or had undergone morbid 

 derangement ere it was invaded. By decay it would 

 appear that it had become converted into material 

 adapted for the nutrition of the fungi, the growth of 

 which had been effectually resisted as long as the 

 tissue remained healthy. If this be so, the fungi 

 cannot be regarded as the cause of the disease, any 

 more than the vultures which devour the carcase of a 

 dead man can be looked upon as the cause of his death. 

 Vegetable germs exist in countless multitudes 



