34 THK FUNCTIONS OF LIFE. 



necessary step towards the existence of the animal 

 world ; as well as a link in the great chain of 

 being, formed and sustained by Almighty power. 

 The Physiology of Vegetables presents many 

 topics of great interest with relation to tinal causes, 

 and will in this Treatise be reviewed with special 

 reference to this important object. 



Nutrition, both in the vegetable and animal sys- 

 tems, comprises a very extended series of operations. 

 In the former it includes the absorption of the crude 

 materials from the surrounding elements, — their 

 transmission to organs where they are aerated, that 

 is, subjected to the chemical action of the air ; — 

 their circulation in the different parts of the plant, 

 — their further elaboration in particular vessels and 

 receptacles — their deposition of solid materials — 

 and their conversion into peculiar products, as well 

 as into the substances which compose the several 

 organs ; — and, finally, the growth and develope- 

 ment of the whole plant. 



Still more various and complicated are the cor- 

 responding functions in animals. Their objects 

 may be arranged under the following general heads; 

 each, again, admitting of further subdivision. The 

 first end to be accomplished is to animalize the 

 food ; that is, to convert it into a matter having the 

 chemical properties of the animal substances with 

 which it is to be afterwards incorporated. The 

 entire change thus effected is termed Assimilation, 

 of which Digestion forms a principal part. The 

 second object is to collect and distribute this pre' 

 pared nutriment, which is the blood, to the diffe- 

 rent organs, or wherever it may be wanted. The 

 necessary motions for these purposes are given to 



