12 THE STRUCTURE AND FUNCTIONS, &c. 



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originates in a cell. During the developement of the villus, 

 this spot or cell was employed only in procuring materials for the 

 growth of the organ. In the perfect animal the formative func- 

 tion of the spot ceases ; its action becomes periodical, active during 

 digestion, at rest during the intervals of that process. The same 

 function is performed, the same force is in action, and the same 

 organ, the cell, is provided for absorption of alimentary matters 

 in the embyro, and in the adult, in the plant, and in the animal. 

 The spongioles of the root, the vesicles of the villus, the last 

 layer of cells on the internal membrane of the included yelk, or 

 the cells which cover the vasa lutea of the dependent yelk, and 

 the cells which cover the tufts of the placenta, are the parts of 

 the organism in which the alimentary matters first form a part of 

 that organism, and undergo the first steps of the organizing 

 process. 



J. G. 



