ALLANTOIS. 175 



In raammiferae I have observed, even at the close of gestation, 

 that the urachus, after traversing the umbilical cord, expands into a 

 smooth tissue, that is porous, and as it were, drilled full of holes, 

 which at last unites intimately with the corresponding surfaces of 

 the membranes between which it is naturally placed. In this crib- 

 riform membrane we meet at other periods with certain pelotons of 

 concrete fatty matter, similar to the hippomanes of horses; and as 

 the bladder opens into it, it unquestionably constitutes part of the 

 allantois. 



There are, therefore, between the sac known as the allantois in 

 the mammiferae, birds, and reptiles, and the reticulated body which 

 I discovered in the human ovum, the most striking agreement in re- 

 spect to resemblance and nature. 



457. In maintaining that the allantois is designed to contain the 

 urine of the foetus, naturalists have in all ages relied chiefly upon its 

 communication with the bladder in brutes, upon the saline taste of 

 the fluid met with in it, and, according to Daubenton, on the uri- 

 nary smell observed in it. I do not think that, even in the vivipa- 

 rous animals, these data are sufficient to establish such an opinion; 

 the urinary odor is a character which is surely too fugacious for 

 us to attach any great importance to it, and on this point is it quite 

 sure that Daubenton was not mistaken? In tlie second place, what 

 does the salt taste prove? Do we not meet with it in the water of 

 the amnios? Was it not communicated by the last named fluid to 

 the former? What connection can there be between the urine and 

 the viscid, fatty, whitish matter contained in the allantois of the bi- 

 sulcae; between the urine and that white, feculent and reticular mass 

 contained in the allantois of the chick about the tenth day of incu- 

 bation; between the urine and the milky, flaky fluid I have observed 

 in the ovum of an adder? Certainly none: to contain the urine is 

 not the only, is not even the chief use of the allantois. 



As to the human species, whether the reticulated body is analo- 

 gous to the allantois, or constitutes a different organ, whether it com- 

 municates with the bladder by means of some channel, or is inde- 

 pendent of it, it appears to me impossible to establish the least affi- 

 nity between tlie substance found in it and the urinary fluid. 



Its functions, like those of the reticulated body, are in my opinion 

 connected with the early nutrition of the germ. Perhaps it serves 

 for the development of some particular organ, or some special appa- 

 ratus; on this subject, we may indulge in a thousand conjectures; but 

 fearing to stray in the field of supposition, I prefer to wait for 

 new facts. I shall content myself with showing that the inner sur- 

 face of the shreds I have turned back on it, were covered with an 



