24 SYLVA AMERICANA. 



existing germs being their source, is at least improbable. He 

 then proves that the " alburnous vessels at their termination 

 upwards, invariably join the central vessels, and that these vessels, 

 which appear to derive their origin from the alburnous tubes, 

 convey nutriment, and probably give existence to new buds and 

 leaves. It is also evident, from the facility with which the rising 

 sap is transferred from one side of a wounded tree to the other, 

 that the alburnous tubes possess lateral, as well as terminal orifices : 

 and it does not appear improbable, that the lateral as well as the 

 terminal orifices of the alburnous tubes, may possess the power to 

 generate central vessels, which vessels evidently feed, if they do not 

 give existence to the reproduced buds and leaves. And therefore, 

 as the preceding experiments appear to prove, that the buds neither 

 spring from the medulla nor the bark, / am much inclined to 

 believe that they are generated by central vessels, which spring 

 from the lateral orifices of the alburnous tubes." By interrupting 

 the circulation in the alburnum, buds may be artificially produced ; 

 and nature has provided means for their reproduction, in those 

 cases where they may have been accidentally destroyed. Several 

 curious facts on this subject may be obtained by an examination 

 of the potato, which like other tuberous roots, are studded with 

 them. 



Buds of all kinds are formed about mid-summer ; after which 

 it has been stated, " that there seems to be a kind of pause in 

 vegetation for about a fortnight." Darwin imagined that a store 

 of nourishing matter is collected during that period, which 

 produces that apparent pause. The season of developement is 

 most usually that of the spring, when nature seems to delight in 

 new products : it is then that the buds are evolved, and enter 

 upon the important functions they are destined to perform. 

 Nothing, however, is known of these functions beyond the general 

 result. Branches, leaves and flowers are produced by buds ; 

 bul what are the particular operations by which these effects are 

 produced ? The answer is easy but unsatisfactory. Buds 

 transpire, and in all likelihood produce the same chemical change 

 on the atmosphere with the other parts of the plant. 



