340 ON RAISING A TREE OF IMPERATRICE NECTARINE. 



lines. I named it the Imperatrice nectarine, because the first fruits 

 which I saw shrivelled much upon the tree ; but those have not 

 subsequently done so more than some other varieties of nectarines. 



I will request that the little tree sent may be planted in fresh 

 unmannred soil without having the branches shortened, and so super- 

 ficially that a part of its roots may remain permanently visible above the 

 soil. The fruit which it will produce will not be nearly as good as that 

 of an older tree ; and it is therefore my wish that some buds should be 

 taken from it in the next season, and inserted into the branches of more 

 mature trees. 



LXXVIII. ON THE PROPAGATION OF TREES BY CUTTINGS IN SUMMER. 



[Head before the HORTICULTURAL SOCIETY, April 3rd, 1838.] 



WHEN a cutting of any deciduous tree is planted in autumn, or winter, 

 or spring, it contains within it a portion of the true, as it has been called, 

 or vital sap, of the tree of which it once formed a part. This fluid, rela- 

 tively to plants, is very closely analogous to the arterial blood of animals ; 

 and I shall therefore, to distinguish it from the watery fluid, which rises 

 abundantly through the alburnum, call it the arterial sap of the tree. 

 Cuttings of some species of trees very freely emit roots and leaves ; whilst 

 others usually produce a few leaves only and then die ; and others scarcely 

 exhibit any signs of life : but no cutting ever possesses the power of rege- 

 nerating, and adding to itself vitally, a single particle of matter, till it has 

 acquired mature and efficient foliage. A part of the arterial sap previ- 

 ously in the cutting assumes an organic solid form ; and the cutting in 

 consequence necessarily becomes, to some extent, exhausted. 



Summer cuttings possess the advantage of having mature and efficient 

 foliage ; but such foliage is easily injured or destroyed, and if it be not 

 carefully and skilfully managed, it dies. These cuttings (such as 

 I have usually seen employed) have some mature and efficient foliage, and 

 other foliage, which is young and growing ; and consequently two distinct 

 processes are going on at the same time within them, which operate in 

 opposition to each other. By the mature leaves, carbon, under the influ- 

 ence of light, is taken up from the surrounding atmosphere, and arterial 

 sap is generated. The young and immature leaves, on the contrary, 

 vitiate the air in which they grow by throwing off carbon ; and they 

 expend, in adding to their own bulk, that which ought to be expended 



