72 Observations on the Natural History 



membrana decidua from the parietes of the uterus, and 

 getting within this hollow viscus. Of all the disco- 

 veries in the mystery of generation, this is by far the 

 most splendid*. An embryon, with its water and invo- 

 lucra, the whole not equiponderant with two grains, 

 forcibly breaking up the attachment of the membrana 

 decidua, and making for itself room in the cavity of 

 the uterus ! Does this embryon force its way by me- 

 chanical powers, or melt down the band of attachment 

 between the lining membrane and wall of the uterus, by 

 certain chemical properties ? 



The sentence in itself is a handsome display of the 

 ability with which some gentlemen are favoured, of 

 making a pretty arrangement of words, without infusing 

 into them the power of making a definite impression on 

 the reader's mind. 



But again to the thesis. " However easy the act of 

 child-bearing may be, among savage tribes, and certain 



* " This resistance will, however, be soon overcome ; either by the 

 ordinary efforts of the tube, or by the ovum resting unusually long, 

 and beginning to develope, obliging the mouth of the tube to open," 

 &c. Museum, V. I, No. 2, p. 172. 



What efforts are these, that can overcome the resistance offered 

 by the attachment of the lining membrane of the gravid uterus? 

 The more the ovum developes, the less the probability of a passage 

 through the mouth of the tube The ovum, under these circum- 

 stances, must remain in the tube, and constitute an extra-uterine 

 foetus. Perhaps the ovum would travel into the uterus, as Dr Har- 

 rison's semen would travel out of it. See Museum, V. I, No. 1, p. 39. 



