Sect. XVI. 3. OF INSTINCT. 103 



by the repeated efforts of our mufcles under the conduft cf our fenja* 



tions or de/ires. 



The chick in the fhell begins to move its feet and legs oa 

 the fixth day of incubation (Mattreican, p. 138)5 or on the 

 feventh day, (Langley) j afterwards it is feen to move itfeif 

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

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

 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 fhut their mouths, (Harvey, Gipfcn, 

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

 of their hairs before their nativity, which however puppies do 

 not, (Swammerdam, p. 3 19. Flemyng Phil. Tranf. Ann. 1755* 

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

 mals are proved to drink part of the liquid in which they fwim 3 

 (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. $8). And 

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

 foetus, and of calves ; and how elfe fhould that excrement be 

 produced in the interlines of all animals, which is voided 1a 

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

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

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

 about three pints, and the hairs amongit it were of the fame col- 

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

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

 tho.fe above mentioned. 



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

 calves and chickens fhould be able to walk by a few efforts al- 

 moft immediately after their nativity : whilil the human infant 

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

 in India, is five or fix months, and in our climate almoil a 

 twelvemonth, before he can fafely fland upon his feet. 



The ftruggles of all animals in the womb muft refemble their 

 mode of fwimminp, as bv this kind of motion thev can bell 

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

 and chicken refembles their manner of walking, which thev have 

 thus in part acquired before their nativity, and hence accompiifh 

 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 anim 

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



fartheft 



