CHAP.XLIII.] LIQUOR AMNII. 6J7 



structures of the chord, in the form of a tubular sheath, which 

 becomes continuous with the integument of the foetus at the navel. 

 The amnion is tolerably transparent, and not very thick ; but often 

 so firm, that it cannot be ruptured very readily. No vessels, nerves, 

 or lymphatics have yet been demonstrated in the healthy membrane; 

 but in some cases of disease it has been found to be highly vascu- 

 lar. M. Coste speaks of the amnion as the " epidermis of the 

 blastoderma." 



The sac of the amnion contains a considerable quantity of an 

 albuminous fluid, the liquor amnii, which, according to Vogt, con- 

 sists of common salt, lactate of soda, albumen, and sulphate and 

 phosphate of lime. Dr. G. O. Eees has found urea in the liquor 

 amnii, and the presence of this substance has been confirmed by 

 other observers. The liquor amnii, at three-and-a-half months, 

 had a specific gravity of 1-0182, and contained 10' 7 7 of albumen in 

 1000 parts; and at six months its specific gravity was 1'0092, 

 and it contained only 6'67 parts of albumen per 1000. 



Liquor Amnii. The liquor amnii enters the mouth of the foetus, 

 and no doubt passes into the trachea as well as the stomach ; but the 

 amount of nutrition which the foetus receives from this source, must 

 indeed be small. At the same time, it is interesting to observe, 

 that the composition of the liquor amnii varies at different periods of 

 pregnancy, as has been shown by Vogt; and during the earlier pe- 

 riods of gestation, the quantity of chloride of sodium is much greater 

 than during the latter part of the time. The proportion of this sub- 

 stance appears to be greater at that period of the development of 

 the embryo, when cell-multiplication and growth is most active. 



Dr. Beale has made, for Dr. A. Farre, an examination of liquor 

 amnii at the eighth month, taken from the body of a woman 

 who died at this period of gestation. The fluid was of a very 

 pale straw colour, slightly turbid, and contained flocculi sus- 

 pended in it. It was quite limpid, and readily dropped from a 

 tube. It was very feebly acid, and remained so for several days 

 after it had been removed. The deposit was subjected to micro- 

 scopical examination, and found to contain many epithelial cells 

 and oil-globules from the vernix caseosa, the soft oily coating with 

 which the skin of the foetus- becomes covered in the latter months 

 of pregnancy. Besides these, there were several clear, transparent, 

 elongated cylindrical bodies, evidently casts of the uriniferous tubes 

 of the kidney of the foetus. This observation proves, very satisfac- 

 torily, that the urinary secretion becomes mixed with the liquor 

 amnii in the human subject. 



VOL. ii. s s 



