236 On the Vital Principle. 



In anfwer to the fecond argument in favour 

 of a vital principle, drawn from the performance 

 of the vital and other involuntary motions, I 

 fhall content myfelf with obferving at prefent, 

 that allowing the organs of thofe motions to be 

 fupplied with nervous energy, which cannot be 

 denied, their motions may be very well ac- 

 counted for, by the ftimulus of their contained 

 fluids*. It may be added, that the principal 

 nerves of the heart and lungs are chiefly fent 

 from the brain: this circumftance, as the parts 

 are fituated very near the fpine, and at a con- 

 fiderable difl:ance from the brain, is a little puz- 

 zling to the vitalifts. 



The force of the third argument, drawn from 

 the want of a brain in full grown foetufes, is 

 taken oflF by Dr. Whytt, who remarks, that as 

 the heart is fometimes wanting in full-grown 

 foetufes, the argument would equally prove, that 

 the heart is not neceflary for the continuance 

 of circulation, as that the brain is not neceflary 

 to the fupport of the fyfliem. Accordingly, 

 foetufes born without a brain do not generally 

 furvive birthf. Dr. Haller fuppofes, with great 

 probability, that in thefe cafes the brain is not 

 wanting originally, but is deftroyed by difeafe, 

 during the growth of the foetus. 



* See page 6. 

 t Haller. Phyf. torn. IV. p. 356. 



Befides 



