144 



ORIGIN OF BUDS. 



on the alburnum formed on the last ; and the buds 



formed in this year are seated on this year's alburnum, 



and on which they remain to be developed in the next 



or some following year. The pith, wood, buds, and 



bark of every shoot are all simultaneously produced. 



But all buds or branches are not primary. Such 



as are produced from an old stem (b, Fig-. 47) whether 



. Fig. 47. 



Example of a primary shoot a, and a secondary shoot b. The 

 former is seated on the alburnum of the first year, the latter on 

 that of the third. 



naturally, or by consequence of pruning-, may be 

 called, for the sake of distinction, secondary*. These 

 can have no immediate connection with the first 

 formed layer of wood and pith, and therefore invari- 

 ably spring- from the envelope. The following deli- 

 neation represents the disposition of the layers of 

 wood and bark, with the places of the primary and 

 secondary buds or shoots, on a section of an abbrevi- 

 ated stem of a tree of three years' growth. 



* Botanists suppose that there are what they call " adventitious 

 buds," that is, if buds come forth from other places than the axils 

 of the leaves or bractea, they are adventitious and new creations. 

 Their appearance, indeed, may be adventitious, but not their 

 identity. If a bud can be produced without a rudiment, so may 

 a whole plant. 



