LKCT. IX.] HVBKKNACULA GEMS. 465 



perennials of tropical climates, in which the in- 

 terval between the formation and the evolution of 

 the bud is so short as to require no protection for 

 the young shoot. 



The scales in some instances are smeared with 

 a resinous matter ; in others they are perfectly free 

 from any moist exudation, but are smooth and 

 polished, being covered with a dry gummy var- 

 nish ; or they are externally hairy, or enveloped in 

 a velvety down. In their organic structure, they 

 closely resemble the scales of bulbs, being com- 

 posed of a layer of cellular substance, enclosed in 

 an epidermis, and containing fasciculi of ves- 

 sels running in lines from the base to the apex. 

 The vessels enter the scale in distinct fasciculi ; 

 and to this arrangement is attributed the differ- 

 ence in figure which always exists between the 

 scale and the real leaf, into the latter of which the 

 vessels enter in one fasciculus only, from which, 

 as from a common centre, they are distributed 

 through the leaf. 



The inner scales perform the functions of the 

 leaves until several of these are expanded, and then 

 they generally drop off; displaying in this respect 

 a striking analogy to seed lobes, which, in many 

 seeds, rise above the surface of the ground, and 

 become green, executing all the functions of 

 leaves until these attain a certain degree of ma- 

 turity; after which they shrivel and fall. The 



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