352 DISEASES OF THE INTESTINES. 



in answer to the obscure questions — hoiv do worms get into 

 the body ? ov, Jioiv are theij bred there ? The ancients 

 entertained notions that they were bred therein through 

 corruption and putrefaction of various matters: such changes 

 as these, however, we now know within a living body can 

 never happen. A more reasonable hypothesis is, that 

 numberless forms and kinds of worms are diffused throughout 

 nature which only await time and place to develop them- 

 selves : this is comparing the worm to the hot, and without 

 the support of any evidence to show that the former, like the 

 latter, undergoes any transformation — that they ever exist 

 in any other than the state of worm ; or, indeed, have the 

 power of existence at all out of the body. What also 

 operates against this notion is, that worms have been seen 

 in the sucking foalj nay, in the foetus even» Linnaeus 

 imagined that both water and earth contained these forms. 

 Some have conceived that animals might transfer worms from 

 one to another through cohabitation. Velisnieri says, 

 animals are bo7^n with worms, and that all have them ; but 

 that the development of them requires a concurrence of 

 favorable circumstances. The worms found in foetuses have 

 been ascribed to hereditariness : in which case the parents 

 must be shown to have some of the same kind; and, after 

 that, a way must be discovered for them to get from one to 

 the other. 



The theory most in favour at the present day is that which 

 ascribes to them spontaneous and unassisted generation ; 

 though this seems one hardly more susceptible of proof than 

 some of the others. There are, however, some ingenious 

 arguments advanced in support of it, such as, worms existing 

 prior to birth ; their incapability of living out of the body ; 

 their presence in difiFerent parts, even in parts the most 

 profound and impenetrable ; the animaFs total unconscious- 

 ness of their presence; each animal having its particular 

 sorts of worms ; and the worms themselves differing in 

 structure from any out of the body, and not being able to 

 subsist on anything but digested alimentary matters and 

 secretions. Now, as hydatids exist which are incapable, for 



