io 4 OF INSTINCT. Sect. XVL 4. 



furtheit advanced before their nativity : but fome animals come 

 into the world more completely formed throughout their whole 

 fyflem them others ; and are thence much forwarder in all their 

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

 perfect animals than die blind puppy, and the naked rabbit ; an.i 

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

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

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

 wren. The parents of the former only find it neceffary 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 facto mentioned in No. 2. of this Section, it is 

 evinced that the foetus learns to fwallow before its nativity ; 

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

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

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

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

 fvvims, is agreeable to its palate, as it confifls of a nouri filing 

 material, (Ilaller. Phyf. T. o. p. 204). It is tempted to expe- 

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

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



• ns, which are attended with coufcioumefs, by the repeated ef- 

 forts of cur mufcles wilder the conducl of our fenfaikns or volitions. 



The infpiration of air into the lungs is io totally different 

 from that of fwaliowing 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 



e placenta, that fuftocating ienfation, which w r e feci about the 

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

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

 into action to relieve this opprefTion ; thofe of the bread, ribj, 

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

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

 often as the opprefTion 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, (Ilaller. Phyf. 

 T. 8. p. 400. ib. pt. 2. p. 1). Mr. BufFcn thinks the action of tl I 

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

 ducing an endeavour to fneeze, may contribute to induce tl 

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

 warmth of the lungs contributes to induce exptiation, (Hill- 

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

 r.'mg a difagrecuble fenfation bv its delays and 1 :onfequenf 



