TRANSACTIONS. 329 



table and aninial forms, placed in the most simple and least 

 elevated ranks of organization, can, in certain favorable 

 circumstances, be formed "without the concurrence of other 

 living bodies, at the expense of the material substance of 

 dead organized bodies, which have been thrown into a com- 

 plete state of revolution by putrefaction and fermentation." 

 Some of these " simple forms" he mentions, such as " infa- 

 sory animalculaB" — varieties of fungi — mushrooms, &c. The 

 doctrine taught by this naturalist and others of his school, 

 •was that some of the very lowest forms of both animal and 

 vegetable growth were produced by chemical agencies 

 alone, without the intervention of the generative act of 

 other similar living beings. But even these writers would 

 not claim this origin for any but the very loioest tribes of 

 the two kingdoms. And having specified a few that he 

 thinks originate thus, the same writer I have already quoted 

 says, '' all living bodies that have not this mode of origin; 

 (i. e. spontaneous generation) proceed from other organ' 

 isms already existing," i. e. are produced by the generative 

 acts of other similar living beings. 



But Harvey, Linna3us and other naturalists had previously 

 announced their conviction "that living bodies can only be 

 propagated by ova, (eggs or seeds) and grains, and that an- 

 imals and vegetables of new formation could be considered 

 only as products of the manifestations of activity of simi- 

 lar beings that were already in existence. 



More recent researches have gone to confirm this view 

 And now in the language of one of the most distinguished 

 writers on general physiology, " it may be . considered as a 

 fundamental truth of physiological science " that every liv- 

 ing crganism has had its origin in a pre-existent organ- 

 ism.^'' " The doctrine of spontaneous generation," says the 

 same writer, " or the supposed origination of organized 

 structures, de nova, out of assemblages of inorganic-parti- 

 cles, although at diflfcrent times sustained with a considera 

 ble show of argument, based on a specious array of factS; 



