io 4 OF INSTINCT. SECT. XVI. 4. 



furtheft advanced before their nativity : but fome animals come 

 into the world more completely formed throughout their whole 

 fyftem than others ; and are thence much forwarder in all their 

 habits of motion. Thus the colt, and the lamb, are much more 

 perfet animals than the blind puppy, and the naked rabbit ; and 

 the chick of the pheafant, and the partridge, has more perfedt 

 plumage, and more perfet eyes, as well as greater aptitude to 

 locomotion, than the callow neillings of the dove, and of the 

 wren. The parents of the former only find it neceflary to (hew 

 them their food, and teach them to take it up ; whilft thofe of 

 the latter are obliged for many days to obtrude it into their 

 gaping mouths. 



IV. From the facts mentioned in No. 2. of this Section, it is 

 evinced that the foetus learns to f wallow before its nativity ; 

 for it is feen to open its mouth, and its ftoinach is found filled 

 with the liquid that furrounds it. It opens its mouth, either 

 inftigated by hunger, or by the irkfomenefs of a continued at- 

 titude of the mufcles of its face j the liquor amnii, in which it 

 fwims, is agreeable to its palate, as it confifts of a nourishing 

 material, (Haller. Phyf. T. 8. p. 204). , It is tempted to expe- 

 rience its tafte further in the mouth, and by a few efforts learns 

 to fwallow, in the fame manner as we learn all other animal ac- 

 tions, which are attended 'with confcioufnefs, by the repeated ef- 

 forts of our mufcles under the- conduct of our fenfations or volitions. 



The infpiration of air into the lungs is fo totally different 

 from that of fwallowing a fluid in which we are immerfed, that 

 it cannot be acquired before our nativity. But at this time, 

 when the circulation of the blood is no longer continued through 

 the placenta, that fuffbcating fenfation, which we feel about the 

 precordia, when we are in want of frefh air, difagreeably af- 

 fects the infant : and all the mufcles of the body are excited 

 into action to relieve this opprefiion ; thofe of the breaft, ribs, 

 and diaphragm are found to anfwer this purpofe, and thus ref- 

 piration is difcovered, and is continued throughout our lives, as 

 often as the oppreffion begins to recur. Many infants, both of 

 the human creature, and of quadrupeds, ftruggle for a minute 

 after they are born before they begin to breathe, (Haller. Phyf. 

 T. 8. p. 400. ib, pt. 2 p. i). Mr. Buffbn thinks the a6tion of the 

 dry air upon the nerves of fmell of new-born animals, by pro- 

 ducing an endeavour to fneeze, may contribute to induce this 

 firft infpiration, and that the rarefaction of the air by the 

 warmth of the lungs contributes to induce expiration, (Hid. 

 Nat. Tom. 4. p. 174). Which latter ir may effect by produ- 

 cing a difagreeable fenfation by its delay, and a confequeut ef- 

 fort 



