the Origin of Intestinal Worms, 356 



siology so long as it prompts to inquiry concerning the mode 

 in which this supposed self-formation takes place ; whilst it is 

 quite the reverse so soon as it closes the eye to any fact which 

 leads to the discovery of the obscure history of parasites. The 

 supposition of undiscovered ova and seeds is certainly contrary 

 to the genius of physiology, when abused by the invention of 

 fanciful theories concerning their appearance ; but this is only 

 allowing that every theory may be abused, not excepting that 

 of equivocal generation, which the history of physiology very 

 sufficiently proves. 



When a naturalist, in spite of all his pains, fails to discover 

 the supposed ova or seeds, it may look like simple truth to as- 

 sert that *' there are none ;" whereas, all that can be legiti- 

 mately inferred is, that he has found none ; and his declara- 

 tion is merely the result of a vain presumption of his ability 

 to penetrate the hidden mysteries of nature. 



It is, generally speaking, much safer to trust to generally 

 prevailing laws, than to confide in such of our observations as 

 are contrary to them. This remark may be applied to the 

 assertion that plants are formed of granite, distilled water, 

 and oxygen, under the influence of solar light. It ought to be 

 remembered, that sometimes, in common life, the appearance 

 or disappearance of a body seems impossible, and still, some- 

 how or other, is effected ; and yet, in such cases, we do not 

 have recourse to equivocal generation. This remark frequent- 

 ly applies to the appearance of higher plants and animals in 

 places where it is impossible to account for them, as after 

 great conflagrations, or the draining of lakes and inlets of the 

 sea, or of fishes in the lakes of volcanic islands. Such facts, 

 however, instead of proving the existence of equivocal gene- 

 ration, ought only to teach us the difficulty of investigating 

 the powers of nature, and demonstrate that we are incapable 

 of accounting for the appearance of such. plants and animals 

 as could not be supposed to be produced by spontaneous gene- 

 ration without absurdity. 



Sect. 4. The Analogy between the supposed Equivocal Gene- 

 ration and Creation refuted. — Creation is sometimes referred 

 to in favour of equivocal generation. The following is the 

 language adopted :— " It is certain a time existed when oven 



