EMBRYO. 191 



488. The experiments of R. de Graaf and Nuck, repeated by 

 Duverney, Haighton and Cruikshank, if they are accurate, have long 

 since demonstrated that the product of fecundation in animals is a 

 vesicle, and that this vesicle takes up some days at least to pass 

 from the ovary to the womb. It is true we are ignorant whether 

 the time that elapses between the vivification of the germ and its 

 arrival in the womb is always the same in the same animal, or 

 whether there is any fixed and certain time for the different species; 

 but it appears that this term is three days in rabbits, and according 

 to MM. Prevost and Dumas, who have lately made numerous re- 

 searches on the subject, that it is from six to seven days in the bitch. 



489. Strato, as Macrobius informs us, supposed that the foetus 

 does not begin to assume the human form until about the thirty-fifth 

 day, when it is as large as a bee. Aristotle teaches that at forty days 

 the embryo is of the size of a large ant; and that we can distinguish 

 its limbs and all its parts, even the penis, if it be a male. It has been 

 stated by others, but less correctly, that from the fifteenth to the 

 twentieth day the embryo is vermiform, oblong, or tumid in the mid- 

 dle. M. Orfila, in speaking of the primitive state of the foetus, is 

 very wide of the truth. The same may be said of M. Meckel when 

 he asserts " that the part that first appears corresponds almost ex- 

 clusively to the trunk; that we only remark at its upper part a small 

 projection, separated from the rest by a notch, and whose thickness 

 is not near equal to that of the middle portion of the body; that the 

 embryo is almost entirely strait, &.c." Ph. Beclard by reproducing 

 the ideas of the celebrated German anatomist, has fallen into the same 

 mistake; nor has M. Adelon been more fortunate in admitting that 

 the embryo exhibits no traces of a head at three weeks, and that the 

 belly appears under the form of a conical projection resting on the 

 inner membrane of the ovum. Nor do I understand why Madame 

 Boivin affirms that " at the tenth day, the embryo is merely a grayish 

 semi-transparent flake, easily liquefied, and of a form difficult to de- 

 termine." It is also certain, that when comparing it to a lettuce 

 seed, or grain of barley, as Burton did, or even to the malleus of the 

 ear like Baudelocque, they could have had before them only preter- 

 natural specimens. 



§. I. Of the Smbryo in General. 



Previously to the end of the first week, there is a striking resem- 

 blance between the human embryo and that of some of the serpents, 

 putting aside the proportional length. It is a curved body, form- 

 ing nearly a complete circle, which in this state may be two or 

 three lines in diameter, but which if straight would be at least four 



