OF INFANCY. 373 



which would be able to live equally in air or in 

 water. 



The air, on its firft entrance into the lungs, 

 generally meets with feme obflacle, occafioned 

 by a fluid fubftance colleded in the wind-pipe. 

 This obftacle is greater or lefs, in proportion to 

 the vifcidnefs of the liquor. But the infan:, at 

 birth, raifes its head, which formerly reclined on 

 its breaft ; and, by this operation, the canal of 

 the wind-pipe is lengthened ; the air, of courfe, 

 rufhes in, forces this fluid into the cells of the 

 lungs, which it dilates; and, in this manner, the 

 mucous fubftance, which oppofed the free paf- 

 fage of the air, is diffufed through the whole 

 fubftance of the lungs. The perpetual admif- 

 fion of frefli air foon dries up this fuperfluous 

 moifturc ; or, if it ihould ftill incommode the 

 infant, it excites a cough, and is thrown off by 

 expedtoration, which generally runs out of the 

 mouth, becaufe the child has not yet ftrength e- 

 nough to fpit. 



We can remember nothing that pafles at this 

 early period of our exiftence. It is, therefore, 

 impoflible to difcover the feelings produced in 

 the child by the ftrft imprefhons of the air. But 

 the cries and groans it utters immediately after 

 birth, are certain indications of the pain occa- 

 fioned by the adion of the atmofphere. Till the 

 moment of birth, the infant is accuftomed to the 

 mild warmth of a tranquil fluid. It is, therefore, 

 confonant to rcafon, that the aclion of a- fluid, 



A a 3 unequal 



