PROCESS OF NUTRITION. CHAP. III. 



the fluids existing in the soil when absorbed by 

 the root, are designated by the appellation of sap 

 or lymph ; which, before it can be rendered sub- 

 servient to the purposes of vegetable nutrition, must 

 either be intermediately conveyed to some viscus 

 proper to give it elaboration, or immediately dis- 

 tributed throughout the whole body of the plant. 

 The object, therefore, of the present section will be 

 that of tracing out the progress of its distribution 

 or ascent. 



Sap proved A very simple experiment will be sufficient to 

 show that the sap is in motion in one direction or 

 other, at least at occasional periods. If the branch, 

 or trunk, or even root of a tree, is laid open 

 or fractured in the course of spring, whether 

 by intentional incision or accidental wound, the 

 sap will immediately begin to flow, and will, in 

 some cases, continue to be copiously discharged 

 perhaps for several days, or at least till the wound is 

 cicatrized ; and if the wound is again opened the 

 sap will flow afresh. This is what is usually de- 



Bythe nominated the bleeding of plants, and is well 

 exemplified in the Vine, Birch, Maple, and Walnut, 

 as affording a most copious discharge. 



But what is the most to be wondered at in the case 

 of the bleeding of plants, is that the most copious 

 discharge does not seem to injure the individual in 

 any material degree. J)u Hamel selected several 

 strong and healthy Vines as the subject of experi* 

 jpent, some of ivhich were trimmed in the usual 



