CADUCA. 157 



surfaces of the womb, and the external one of the chorion, which it 

 lines for nine months? Finally, to decide the question, it should 

 suffice us to remember that the characters of this singular membrane 

 are in every respect similar, at the moment of parturition, to what 

 they were at the commencement of pregnancy, a period wherein 

 nobody has pretended to have seen a trace of organisation. 



409. If then the caducous membrane is not an organic membrane, 

 if it is merely an adventitious coat, as M. Blainville calls it, or the 

 result of a concretion taking place in the uterus, the name of an- 

 histous* membrane which I propose to bestow upon it, and which 

 is synonymous with inorganic membrane, appears to me to be the 

 only one that can be advantageously applied to it. 



410. Uses. I shall not stop to combat the opinion of those who 

 think that the anhistous membrane serves to nourish the foetus dur- 

 ing the first weeks of its existence; to remark that the umbilical 

 cord is always inserted on that portion of the ovule which is not 

 covered with this concretion, ought to be sufficient to demonstrate 

 that it is unconnected with the nutrition of the first lineaments of the 

 foetus. Its use is to sustain the vesicle on some one point of the 

 uterine cavity. I know it may be objected that it fixes and main- 

 tains itself as firmly in animals as in women, and just as well in 

 extra-uterine as in natural pregnancy; but in brutes, the surface of 

 the ovule, and the form of the parts through which it has to pass, 

 are far from being in all respects similar to those that are noticed 

 in the human species. The uterine horns in brutes difller from the 

 human uterus in this respect, that they never dilate enough to per- 

 mit the germ that passes through or stops in them to be in contact 

 with all the points of the circle to which it corresponds, in one of 

 those organic tubes. Further, when the product of fecundation 

 accidentally develops itself in the peritoneum, or the tube, or even 

 in the substance of the uterus, it remains uniformly contiguous to the 

 walls of the cavity which it has appropriated; so that the caduca, 

 such as I understand it, is not at all necessary in these two circum- 

 stances, and its absence, therefore, does not at all prove that in re- 

 lation to ordinary gestation it has not the uses I have just assigned 

 to it. 



Another use of the anhistous membrane seems to me to be to 

 circumscribe the placenta, and determine the place of its insertion; 

 but I defer the examination of this point to another article. 



411. Analogy. Those who have embraced the opinion of Hun- 

 ter have asserted that the caduca does not exist except in wo- 



* From itTTo; tela, and a, privative. 



