154 PRINCIPLES OF GARDENING. [CH. V. 



branch, to every leaf, and to every finiit of the 

 plants, gradually acquiring during its passage a 

 greater specific gravit}^ not only by exlialation, but 

 by dissolving the peculiar secretions of the plant 

 formed during its previous year's growth, and de- 

 posited in the alburnum from the sap, during its 

 downward course in the inner bark from the leaves. 

 It is in the leaves that the chief elaboration of the 

 sap takes place, and those peculiar juices are formed 

 characteristic of the plant, and which are found 

 deposited there, or in the bark, or still further altered 

 in the fruit and seed. 



Although the sap increases in specific gi'avity, and 

 consequently obtains an accession of solid matter 

 duiing its progress up the stem, yet the matter thus 

 obtained is not of paramomit importance, nor abso- 

 lutely controlling the subsequent changes to be 

 effected, for in such case the greengage would be 

 altered by its plum stock, and the nonpareil by its 

 crab stem. So far from this being the case, the 

 old gardener's maxim, "the graft overruleth the 

 stock quite " is consonant with truth, though it is to 

 be taken with some reservation. The graft prevails 

 and retains its qualities, yet the stock has the power 

 of influencing its productiveness as well as the 

 quality of the fruit. Thus, a tree having an expan- 

 sive foliage and robust growth, indicative of large 

 sap vessels and vigorous circulation, should never be 



