SECT. XVI. 3. OF INSTINCT. 103 



by the repeated e forts of our mufcles under the conduft of ourfenfa- 

 tlons or defires. 



The chick in the (hell begins to move its feet and legs on 

 the fixth day of incubation (Mattreican, p. 138); or on the 

 feventh day, (Langley) ; afterwards it is feen to move itfelf 

 gently in the liquid that furrounds it, and to open and (hut its 

 mouth, (Harvei, de Generat p. 62, and 197. Form. dePoulet. 

 ii p 129). Puppies before the membranes are broken, that 

 involve them, are feen to move themfelves, to put out their 

 tongues, and to open and {hut their mouths, (Harvey, Gipibn, 

 Riolan, Haller). And calves lick themfelves, and fwallow many 

 of their hairs, before their nativity, which however puppies do 

 not, (Swammerdam, p. 319. Flemyng Phil. Tranf. Ann. 1755. 

 42). And towards the end of geflation, the fcetufes of all ani- 

 mals are proved to drink part of the liquid in which they fwim, 

 (Haller. Phyfiol. T. 8. 204). The white of egg is found in 

 the mouth and gizzard of the chick, and is nearly or quite 

 confumed before it is hatched, (Harvei de Generat. 58). And 

 the liquor amnii is found in the mouth and ftomach of the human 

 fcerus, and of calves ; and how elfe ihould that excrement be 

 produced in the inteftines of all animals, which is voided in 

 great quantity foon after their birth j (Gipfon Med. Effays, 

 Edinb. V. i. 13 Halleri Phyfiolo^. T. 3 p. 318. and T. 8.) 

 In the flomach of a calf the quantity of this liquid amounted to 

 about three pir.ts, and the hairs amongft it were of the fame col- 

 our with thofe on its fkin, (Blafii Anat. Animal, p. m 122). 

 Thefe facls are attefted by many other writers of credit, befides 

 thofe above mentioned. 



III. It has been deemed a furprifing inftance of inftinft, that 

 calves and chickens (hould be able to walk by a few efforts ai- 

 med immediately after their nativity : whilft the human infant 

 in thofe countries where he is not encumbered with clothes, as 

 in India, is five of fix months, and in our climate almoft a 

 twelvemonth, belbre he can fafely ftand upon his feet. 



The llruggles of all animals in the wcmb muft referable their 

 mode of fwimming, as by this kind of motion they can beft 

 change their attitude in water. But the fwimming of the calf 

 and chicken refembles their manner of walking, which they have 

 thus in part acquired before their nativity, and hence accomplifli 

 it afterwards with very few efforts, whilft the fwimming of the 

 human creature refembles that of the frog, and totally differs 

 from his mode of walking. 



There is another circumftance to be attended to in this affair, 

 that not only the growth of thofe peculiar parts of animals, 

 which are firft wanted to fecure their fubfiftence, are in general 



furtheft 



