PROCESS OF NUTRITION. CHAP. III. 



composition of water. Still, however, there is no 

 proof that this decomposition was direct ; but rather 

 there is reason to suppose that the leaf formed in 

 the sun carbonic acid gas from its own substance, 

 and that the oxygene was extricated by the decom- 

 position of this gas : for in the progress of a similar 

 experiment, when a vessel filled with potass was 

 suspended in the receiver, the formation of oxygene 

 was stopped ; it is plain, therefore, that carbonic acid 

 gas was forming, and that the oxygene which ap- 

 peared was produced from its decomposition. 



SECTION VIII. 



Descent of the Proper Juice. 



Itsanalogy WHEN the sap has been duly elaborated in the 

 Wood of l ea f by means of the several processes that have just 

 animals, ^ een described, it now assumes the appellation of 

 the Cambium, or Proper Juice of the plant. In this 

 ultimate state of elaboration it is found chiefly in 

 the bark, or rather between the bark and wood, and 

 may .very often be distinguished by a peculiar 

 colour, being sometimes white, as in the several 

 species of Spurge, and sometimes yellow, as in 

 Celandine. It is said to be the principal seat of the 

 medical virtues of plants ; and was regarded by 

 Malpighi as being to the plant what the blood is to 

 the animal body the immediate principleof nourish- 

 ment, and grand support of life ; which opinions he 



