Jan. 1899. J BOTANICAL SOCIETY OF EDI J. BURGH 157 



section of one of those buds showed a structure agreeing 

 in every respect with the apical or whorl buds, except 

 that the bud is joined to the branch of limited growth 

 by a narrow neck, which gives a peculiar constricted 

 appearance to its base. A section of the undeveloped 

 interfoliar bud in the normal condition shows simply a 

 papilla of cells occupying the apex of the shoot between 

 the bases of the two needles. Its primary leaves are not 

 changed to scales, nor does it develop under ordinary 

 conditions. "We have evidently a bud here agreeing very 

 closely in structure and function with the dormant whorl 

 bud, and might reasonably expect it to produce the same 

 results. But authorities differ very widely on this point, 

 some say that interfoliar buds produce branches of un- 

 limited growth, and that dormant buds produce only 

 rosette shoots, while others say that Iwth can produce 

 branches of unlimited growth. 



My observations tend to show that both cryptoblasts 

 and brachyoblasts can produce either kind of branch, 

 the results varying with the conditions under which the 

 buds are -induced to develop and the general health of the 

 tree at the time. We have seen that complete defoliation 

 by insects can cause dormant buds to develop, also that an 

 accession of nutriment may have the same effect ; but in the 

 former case a rosette shoot results in, in the latter, a branch 

 of unlimited growth. The reason for this is not far to seek. 

 In the first case, the vitality of the tree has received a 

 severe check, and there is neither time nor energy left 

 for the formation of bifoliar spurs in the axils of the 

 primary leaves, so we get a rosette shoot. In the second 

 case, the conditions are more favourable, and buds are 

 formed in the primary leaf axils, with the result that 

 we get branches of unlimited growth. This holds good for 

 the brachyoblasts also. That the health and vigour of the 

 tree aftects the formation of axillary buds is shown even in 

 the seedling. At the end of the first year weak plants 

 form only an apical bud, stronger plants form, in addition 

 to this, buds in the axils of their primary leaves, which in 

 even stronger plants may develop. If at this early stage 

 the bifoliar-spur needles are destroyed by insects, the 

 brachyoblast develops into a shoot covered with primary 



