ANIMAL PARASITES. 61 



may not also be highly deleterious, either to all persons, 

 or to some, as the result of idiosyncrasy. In my opinion, 

 it would be a prudent course to reject potatoes which are 

 much affected with fungi, either for the use of man or 

 beast. 



(243.) I have viewed with great interest the relation of 

 the fungi to the diseased potatoe ; I have seen these exqui- 

 sitely beautiful parasites proceeding from that which would 

 otherwise have been offensive and disgusting ; and thus, 

 when the diseased tuber becomes unfit to nourish the body, 

 the parasite that emanates from its decay may furnish to 

 the mind matter for observation and study replete with in- 

 terest. 



CHAPTER X. 



RELATION OF GANGRENE TO ANIMAL PARASITES. 



Numerous species of insects on potatoe plant C244) Acarus (245). 

 Coccinella, ichneumons, flies (247). Aphis (248). 



(244.) THE relation of this gangrene of the potato'e to ani- 

 mal parasites must also be carefully examined. Flies will 

 sometimes lay their eggs in rotten potatoes, various infusorial 

 animalcules may very probably be produced in them, and 

 if the potatoe plant be carefully examined, numerous insects 

 may be discovered upon it. 



(245.) A very common insect, which is constantly to be 

 seen upon tubers, is a small Acarus, which runs about the 



