QO PROCESS OF NUTRITION. CHAP. III. 



are covered with an epidermis, or fine and transpa- 

 rent pellicle, which has been described by some 

 phytologists as being of so close and compact a 

 texture that the eye, aided even by the best micro- 

 scopes, is unable to discover in it the slightest vestige 

 of pores or apertures. Hedwig and Decandolle 

 have, however, detected pores in the epidermis of 

 the leaves of many plants, and they may readily be 

 detected by any one who will be at the trouble of 

 employing the same means. It does not appear 

 that any pores have been yet detected in the epider- 

 mis of the root ; though we must not on that account 

 conclude that it is not porous. We must even, on 

 the contrary, admit that it is furnished also with 

 pores, as well as the epidermis of the leaf; because 

 the whole of the nourishment which the plant de- 

 rives from the soil must of necessity pass through it. 

 Absorbing But if the pores of the epidermis are so very fine 

 fl^idsf * lg as either to elude the sight, or to be discoverable 

 only by the application of the highest magnifying 

 powers, they can be permeable only to fluids ; and 

 if so, then the food of the plant can be taken up 

 only by absorption or inhalation, as the chyle into 

 the animal lacteals, or the air into the lungs. The 

 former term will be applied to the intro-susception 

 of non-elastic fluids ; the latter, to that of gaseous 

 fluids. 



Non-elas- Of the fact of the absorption of non-elastic fluids 



absorbed ^Y tne epidermis f plants any one may easily 



satisfy himself, merely by immersing in water a plant 



