SECT. XXX VIII. 3 . OXYGEN ATION OF BLOOD. 539 



In confequence the placenta is produced for fome 

 other important purpofe. 



Firft, that the liquor amnii is riot an excrementi- 

 tious fluid is evinced, becaufe it is found in greater 

 quantity, when the fetus is young, decreafmg after 

 a certain period till birth. Haller alTerts, " that 

 in fome animals but a frriall quantity of this fluid 

 lemains at the birth. In the eggs of hens it is 

 confumed on the eighteenth day, fo that at the ex- 

 clufion of the chick fcarcely any remains. In rab- 

 bits before birth there is none." Elern. Phyfiol. 

 Had this been an excrerrientitious fluid, the contrary 

 would probably have occurred. Secondly, the fkin 

 of the fetus is covered with a whitifh cruft or pel- 

 licle, which would feem to preclude any idea of the 

 liquor amnii being produced by any exfudation of 

 perfpirable matter. And it camiot confift of urine, 

 becaufe in brute animals the urachus pafles from 

 the bladder to the alantois for the exprefs purpofe 

 of carrying off that fluid ; which however in the 

 human fetus feems to be retained in the diftended 

 bladder, as the feces are accumulated in the bowels 

 of all animals. 



i. The nutritious quality of the liquid, which 

 furrounds the fetus, appears from the following con- 

 fiderations. I. It is coagulable by heat, by nitrous 

 acid, and by fpirit of wine, like milk, ferum of blood, 

 and other fluids, which daily experience evinces to 

 be nutritious. 2. It has a faltifh tafte according to 

 the accurate Baron Haller, not unlike the whey of 

 milk, which it even referable* in fmell. 3. The 

 white -of the egg which conftitutes the food of the 

 chick, is fhewn to be nutriiious by our daily expe- 

 rience ; befides the experiment of its nutritidus ef- 

 fects mentioned by Dr. Fordyce in his late Treatife 

 on Digeftion, p. 178; who adds, that it much re- 

 fembles the eflential parts of the ferum of blood. 



VOL. I. Nn 3. A 



