37P OXYGENATION SECT. XXXVIIL 3. i. 



moid and aerated furface of the earth, and of the latter in the 

 ever-changing and ventilated water, may not be in need of an 

 apparatus for the oxygenation of their firlt blood, before the 

 leaves of one, and the gills of the other, are produced for this 

 purpofe. See Phytologiaj Se6r,. III. 



III. I. There are many arguments, betides the drift analogy 

 between the liquor amnii and the albumen ovi, which (hew the 

 former to be a nutritive fluid ; and that the fetus in the latter 

 months of pregnancy takes it into its ftomach ; and that in con- 

 fequence the placenta is produced for fome other important 

 purpofe. 



Firft, that the liquor amnii is not an excrementitious fluid is 

 evinced, becaufe it is found in greater quantity, when the fetus 

 is young, decreafmg after a certain period till birth. Haller af- 

 ferts, " that in fome animals but a fmall quantity of this fluid re- 

 mains at the birth. In the eggs of hens it is confumed on the 

 eighteenth day, fo that at the exclufion of the chick fcarcely any 

 remains. In rabbits before birth there is none." Elem. Phyfiol. 

 Had this been an excrementitious fluid, the contrary would 

 probably have occurred. Secondly, the fkin of the fetus is cov- 

 ered with a whitim cruft or pellicle, which would feem to pre- 

 clude any idea of the liquor amnii being produced by any exu- 

 dation of perfpirable, matter. And it cannot 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. 



2. The nutritious quality of the liquid, which furrounds the 

 fetus, appears from the following confiderations. i. Itisco- 

 agulable 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 refembles in fmell. 3. The white of the egg which 

 conftitutes the food of the chick, is (hewn to be nutritious by 

 our daily experience ; befides the experiment of its nutritious 

 efFefts mentioned by Dr. Fordyce in his late Treatife on Di- 

 geftion, p, 178 ; who adds, that it much refembles the effential 

 parts of the ferum of blood. 



3. A fluid fimilar to the fluid, with which the fetus is fur- 

 rounded, except what little change may be produced by a begin- 

 ning digeftion, is found in the fame manner in the ftomach of 

 the chick, 



Numerous hairs, fimilar to thofe of its Ikin, are perpetually 



found 



