AND ANIMAL LIFE. 97 



and new-born infant is great. The latter is bring- 

 ing into play, by the exercise of its limbs, and 

 the stimulus of external objects, the endowments 

 of the nervous system, while the former has no ne- 

 cessity for them. But there is no difference what- 

 ever between the foetus and the infant in regard 

 to those systems by which an animal is nourish- 

 ed. One is supplied with arterial blood from its 

 mother, and this is distributed to every part of 

 the body ; the vital principles of which it is com- 

 posed are appropriated to the increase of the em- 

 bryo parts precisely in the same manner as when 

 these parts are subsequently developed and main- 

 tained by blood elaborated by its own organs. 

 The nervous system is as little related in after 

 life as at that time to those peculiar adaptations 

 by which one general fluid is converted into the 

 varieties which the constitution exhibits. It will 

 produce modifications, because it supplies sensi- 

 bility and motion, whose influence is extensive 

 and multiplex. 



LXXXIV. It is therefore obvious, that the dif- 

 ficulty, of which WILSON PHILIP speaks, is a diffi- 

 culty only according to his own principles. The 

 solution which is here given is not derived from 

 hypothetical sources, but is furnished by the same 

 reasoning and observations which have enabled 

 us to expose evident inaccuracies in the views 

 which he has developed, as explanatory of the 

 process of digestion and the generation of animal 

 heat. G 



