204 METAMORPHOSES OF MAN 



inhabit all forms of animals indifferently. These 

 theoretical inductions are fully borne out by ex- 

 perience. Every animal supports, so to speak, its own 

 particular Helminthes. If we were to enumerate all 

 these parasites, we should review the entire creation, 

 and should pry into the inmost bodily recesses of all 

 other animals. 



But whence come these strange beings, which 

 attack the tissues and viscera in myriads, which 

 penetrate the cavity of the skull, and even that of the 

 eyes ! Destined to lead an exceptional and, so to 

 speak, second-hand existence, is it possible that they 

 are produced and propagated like other animals, in 

 fact like the very beings to which in truth they may be 

 regarded as parasitic appendages ? To reply to these 

 questions, is to touch on another which is far more 

 general, and which science has always handed down 

 from age to age, to our times in which alone its 

 solution could be attempted. 



Is the creative power which has given rise to living 

 beings extinct, or is it still exerted on this globe ? In 

 other words, is the phenomenon styled equivocal or 

 spontaneous generation a reality ? 



We know the reply of the ancients. They supposed 

 that all bodies in a state of putrefaction developed 

 new organisms, and Aristseus' fable was only a special 

 application of a general doctrine. These ideas uni- 

 versally adopted spread almost to our own days. It 

 required the experiments and observations of Redi 

 and Vallisnieri to convince the savans of the seven- 

 teenth and eighteenth centuries, that insect larvce 

 were not a product of decomposition. 



From that period, more correct ideas concerning 



