ALLANTOIS. 173 



sort of reticulated magma. By pressing upon it with the dissect- 

 ing needle, I squeezed from it some particles of a whitish pulpy- 

 matter; upon detaching it from the chorion, I found it adhered to it 

 by some very delicate and fragile filaments; that its adherence to 

 the amnios and vitelline sac was less regularly established; lastly, 

 that it also enveloped the cord on which the amnios was not as yet 

 folded, and that it could be traced to the belly of the embryo, as far 

 as the pedicle of the umbilical vesicle. 



453. It is rare, exceedingly rare, to have an opportunity of ex- 

 amining so perfect a product of conception; M. Henoque, however, 

 procured one for me that was still more so. This ovum, three or 

 four weeks old, and very recent, had undergone no change of shape, 

 nor laceration; immediately under the chorion there was a tissue of 

 a dull white color, extremely delicate, and almost as easy to tear as 

 the retina. Notwithstanding all the care taken, it was ruptured 

 merely by the pressure I made upon another point of the ovum in 

 dividing the chorion. It was full of an emulsive or cream-like sub- 

 stance of a slightly yellowish white, and which tended to escape in 

 homogeneous grumes. Its inner surface gave birth to fibres and 

 lamellae, and to numberless prolongations which decussated in every 

 direction, like what is observable in the spleen, the seminal gland, 

 the corpora cavernosa, and as is said to be the case also, in the 

 hyaloid membrane of the eye. These filaments, after traversing the 

 semi-fluid white matter, proceeded to a second lamella, which, with- 

 out any intermedium, was in contact with the periphery of the am- 

 nios, of the umbilical vesicle, and of its pedicle. Certain isolated 

 shreds, being washed and floated, exhibited an almost perfect trans- 

 parency, and much less thickness than the amnios. 



454. To sum up, this new organ constituted a sac with a double 

 coat, moulded upon the cavity of the chorion, enclosing the umbili- 

 cal vesicle and the amnios, after the manner of the serous mem- 

 branes, forming interiorly a true net work with large unequal 

 meshes, in which the emulsive fluid was lodged. Its two coats, se- 

 parated at one place by a distance of more than three lines, became 

 more and more proximate towards the root of the umbilical cord; 

 near the belly they appeared to be confounded with each other, but 

 their extreme tenuity prevented from ascertaining what organ of the 

 abdomen they were continuous with. 



Have I now any right to conclude that this body was really the 

 allantois? It is true I did not succeed in demonstrating its commu- 

 nication with the bladder, but this communication has been no bet- 

 ter demonstrated in reptiles, and even in many of the mammiferae; 

 moreover, the bladder itself was so small, or so little developed in 

 .16 



