404 ON THE ORIGIN OF ENTOZOA, &c. 



committed to the charge of the female are often hatched without 

 her care, knowledge, or superintendence ; and to suppose 

 that their parasitical inhabitants are derived from eggs trans- 

 mitted to them by the parent, is a figment of the imagination. 

 This hypothesis is inapplicable, and disproved in the case of 

 viviparous worms. 



I mentioned in an early part of my paper, that in some of 

 the worms no genital apparatus nor ova are manifest ; these, 

 therefore, being solitary, and enclosed in a cyst, do not seem 

 to propagate, and here the hypothesis is overturned, seeing 

 that they are not transferable. But as the ovules and genital 

 apparatus, even in these, may really have existence, although 

 not manifest, I will not lay much stress upon this, but pass 

 over it in silence. 



But there are Entozoa, and not a few, who actually do bring 

 forth living young ; and that these young are transferred by 

 the absorbents and blood vessels to the uterus and ovaries in 

 the Mammalia, or in the case of Amphibia and fishes, that 

 they insinuate themselves into the ova, is a position which no 

 man would contend for, or judge probable, however biassed by 

 prejudice or enamoured of theory he may be. The argument 

 is, in my humble estimation, convincing and unanswerable ; 

 for even supposing that the germs of these viviparous worms 

 were prematurely born, (that is, before the contained animals 

 were endowed with life,) and were in this state deposited and 

 carried into the circulating current ; even supposing this, I 

 say, a proof would yet be wanting that such an abortion could 

 be afterwards vivified. 



We are now brought to the conclusion — that the eggs of 

 worms are not communicated to infants and foetuses, either by 

 the male or female parent ; that it is as false and irrational to 

 imagine that they have been transmitted from generation to 

 generation, from the primordial parents either of man or other 

 animals, as to suppose that they have been carried into the body 

 from an extrinsic source. 



The reader is, I doubt not, by this time sensible of the great 

 difficulties with which this problem is beset, and must perceive 

 that if my positions be true, viz. that worms do not gain access 

 to animals by the mucous cavities, nor are they transmitted by 

 the parents, to their young, that the doctrine of spontaneous 

 generation is inevitable. But as this is a doctrine inconsistent 



