94 THE NUTRITIVE FUNCTIONS. 



reflect for one moment. The food in the stomach and in- 

 testines is as much external to the living body as it was 

 before its introduction into those cavities, until it is taken 

 up by the absorbents which line their walls ; and it is re- 

 moved from those cavities by the radicals of the chyliferous 

 vessels and afterwards diffused to all parts of the animal, 

 just as the roots of plants absorb food from the soil, which 

 is.afterwards conveyed by the trunk to the branches and 

 highest extremities. " Whilst, therefore, the roots of 

 plants, ramify through the soil in quest of food, fixing the 

 plant to its surface, animals which wander about from place 

 to place in search of the food which they require, may be 

 truly said to carry their soil about with them."* 



THE CIRCULATION IN PLANTS AND ANIMALS. 



In the lowest forms of animals and vegetables where 

 the structure is wholly cellular, the movements of the nu- 

 tritive fluid equally pervade all parts of the organism, pro- 

 ceeding forward and laterally from cell to cell without fol- 

 lowing any particular course. Such is also the condition 

 of the circulation in the higher animals and plants during 

 the embryonic stage of development; this, however, is 

 with them only a transient condition of things. As growth 

 progresses in the seed or ovum, the cells begin to manifest 

 their individual peculiarities, and the young plant or ani- 

 mal finally ruptures the envelopes more or less resisting, 

 which cover it, and speedily develops those organs neces- 

 sary to its life and increase. As specific processes are car- 

 ried on in distant parts of the organism, it is necessary 

 that the nutritive juice should be conveyed in the proper 

 channels, which develop accordingly for this purpose. In 



* Carpenter. 



