118 VEGETABLE SAP. 



enough to admit such a surcharge. The sap in the 

 branches is not visibly diminished by this supposed 

 subsidence ; and what is more against the idea than 

 any thing else, is the stubborn fact, that the motion 

 of the sap begins at the top of the tree before it is at 

 all liquefied at the bottom, which could not happen did 

 the returning tide flow from the roots. The best 

 argument in support of the subsidence of the sap is 

 that used by the carpenter respecting the quality of 

 winter and summer felled timber: but this will be 

 answered under the section Felling. We may, how- 

 ever, observe here, that if there were any apparent 

 necessity for such subsidence we ought, unhesitatingly, 

 to concur in believing it. We are well aware that those 

 who believe that the elaborated sap descends, also be- 

 lieve that it is chiefly disposed of in the formation of 

 the new zone of wood along the whole length of the 

 stem and roots ; so that the carpenter's idea of it all 

 sinking to the roots is abandoned: but, if our eyes 

 have not greatly deceived us, we have observed that 

 this same new zone of wood is formed and replete 

 with sap, before the time arrives at which the sap is 

 said to take its downward course. And, indeed, ex- 

 cept in the case of herbaceous perennials (admitting 

 the opinion true with respect to them) it appears to 

 us, that the subsidence of the sap, in other cases, 

 is superfluous, and contrary to the usual operations 

 of nature. 



Upon the whole we are led to conclude that the 

 sap is composed of fluids chiefly imbibed by the roots ; 



