402 ON THE ORIGIN OF ENTOZOA 



with them ; this being assumed, by far the greater portion of 

 them must either perish, or by an error loci, be deposited in 

 uncongenial situations, and fail in reaching the place of their 

 destination. The loss which the ovules would sustain in thus 

 being whirled round in the circulating torrent is prodigious 

 and inconceivable. In no microscopic examination either of 

 the minute vessels or their contained fluids have parasitical 

 ovules been discovered — 



" Transeat cum ceteris." 



Are the ovules transferable from the uterus or ovaries to the 

 foetus ? 



All the difficulties inseparable from the preceding arguments 

 apply with increased force when brought to bear on this ques- 

 tion. Granting that the ovules are in fact brought together in 

 the embryo, to conceive a process by which they are to be 

 deposited in the different situations they are destined to occupy 

 in the embryo bids defiance to the powers of human imagina- 

 tion. In the livers of the foetal lambs the Distoma hepaticum 

 has been found. The ovules of these, therefore, to be 

 transferred from the uterus to the foetus, must have passed 

 through the absorbent vessels, the arteries and the veins, and 

 from these into the vena portse and pori biliarii ! ! How impro- 

 bable ! We have to contend with a greater difficulty, when we 

 remember that many occupy the brain and other inaccessible 

 situations ; and still a greater presents itself when we call to 

 mind that the ovules are propelled to every part of the body, 

 until they attain a congenial settlement, which some of them 

 (as before mentioned) could not have attained till after the 

 lapse of several generations. 



The obstacles are equally great if it be said that the eggs of 

 worms are communicated from the mother to her offspring by 

 the milk, or by any other means. 



The doubts which I have thrown on this theory, in its 

 application to man and the larger Mammalia, become increased 

 when applied to the rest. By far the majority of the foetal 

 Mammalia undergo protracted utero-gestation, and then 

 commence lactation ; in a few, the family Didelphida for 

 instance, the young resort to the mammae in a very tender 

 state. Those authors who have been made sensible of the 

 difficulties attendant on the transportation of the ovules from 



