20 GEMMATION. 



development of one apical bud at the end of the shoots whether terminal 

 or lateral, and of a circlet around it at the base. In the erect leader the 

 circlet is complete, but in the lateral branches it usually happens as seen 

 in the species of Abies and Picea, that the uppermost buds of the circlet, 

 if developed at all, remain in a rudimentary condition. This is evidently 

 connected with the horizontal position of the branches ; but it is curious 

 to note that it is the uppermost buds, those most exposed, that are not 

 developed, but are checked in their growth to the advantage of the 

 lower buds. 



In Pines, on the other hand, the lateral buds in the first instance are 

 erect like the terminal bud; but as they grow they assume a horizontal 

 direction as in the species of Abies, but with this important exception, 

 that they generally turn up at the tips as growth goes on, and thus 

 allow of the access of light to the branches beneath. Hence in Pines 

 we find the circlet of buds, whether on the terminal or on the lateral 

 shoots, complete and equally developed on all sides. The relative absence 

 of lateral buds, except near the ends of the shoots, is also a marked 

 feature in the Abietinese. 



The bud scales are arranged spirally and are frequently compacted 



together by a felted arrangement of 

 the hairs or fringed margins of the 

 scales as in many Pines, or by an 

 exudation of resin as in many Firs. 

 These arrangements are evidently 

 adapted for the protection of the 

 young buds from cold or wet. In 

 some Spruce Firs, additional protec- 

 tion is afforded by the arrangement of 

 the leaves near the end of the shoot, 

 and which, .instead of spreading 

 laterally, are directed parallel to the 

 long axis of the shoot, and thus close 



Fig. 6. 1, Tubular. 2, Calyptrate deperulation. over the buds. The form of buds 



and bud scales sometimes afford useful 

 means of discrimination between certain species. 



The bud scales, or perulse as they are technically called, present 

 variations in texture and duration, being coriaceous in some species, long, 

 thin and membraneous in others; they are either entire, fringed or 

 lacerated at their margins. As these perulas serve a uniform and 

 temporary purpose only, they are less liable to variation and modification 

 during growth from the operation of external causes, than organs of 

 lono-er duration and more complex function, and hence, from their 

 relative invariability, their utility for classificatory purposes is greater 

 than might be supposed. 



The manner in which the bud scales are removed or thrust aside by 

 the orowiiio- shoot is also worthy of attention. The variations observed 

 depend of course, on the relation between the nature of the scale, 

 the amount of resistance they offer, and the degree of vigour and 

 direction of o TO wth in the bud beneath. In some cases the bud scales 

 are least resistant to the pressure of the growing shoot at the apex of 

 the bud, in which case the shoot makes its way through a ring or tube 

 of scales which persist around the base of the branch for a long time. 

 Illustrations of this occur in Abies amaUlis, A. noWte, A. Frasen, 



