AMNIOTIC FLUID. 305 



wliieli contain a few fine, fatty granulations. At term, the 

 amnion adheres to the chorion, though it may be separated, 

 with a little care, as a distinct membrane, and may be stripped 

 from the cord. From its arrangement and from the absence 

 of blood-vessels, it is evident that this membrane is simply 

 for the protection of the foetus and is not directly concerned 

 in its nutrition and development. 



The gelatinous mass referred to above, situated, during 

 the early periods of intra-uterine life, between the amnion 

 and the chorion, presents a semifluid consistence, and is 

 marked by the presence of numerous very delicate, interlac- 

 ing fibres of young connective tissue and fine, grayish granu- 

 lations scattered through its substance. These fibres gradu- 

 ally develop as the quantity of gelatinous matter diminishes 

 ai-d the amnion approaches the chorion, until, finally, it 

 forms a rather soft, reticulated layer, which was described 

 by Bischoff, under the name of the membrana media. 1 



Amniotic Fluid. The process of enlargement of the 

 amnion shows that the amniotic fluid gradually increases in 

 quantity as the development of the foetus progresses. At 

 term, the entire quantity is variable, being rarely more than 

 two pints or less than one pint. 2 In the early periods of 

 utero-gestation, it is clear, slightly yellowish or greenish, and 

 perfectly liquid. Toward the sixth month, its color is more 

 pronounced, and it becomes slightly mucilaginous. Its reac- 

 tion is usually neutral or faintly alkaline, though sometimes 

 it is feebly acid in the latest periods. It sometimes contains 

 a small quantity of albumen, as determined by heat and nitric 

 acid ; and there is generally a gelatinous precipitate on the 

 addition of acetic acid. The following table, compiled by 

 Robin, gives its chemical composition : 



1 BISCHOFP, Traite du developpement. Encyclopedic anatomique, Paris, 1843, 

 tome viii., p. 167. 



ROBIN, Mcmoire sur la structure intime de la vesicule ombilicale. Journal de 

 la physiologic, Paris, 1861, tome iv., p. 306. 



2 ROBIN, Le$ons sur les humeurs, Paris, 1867, p. 779. 



