114 BUDS AND STIPULES 



scale along the posterior face allows it to prolong its 

 period of protection. 



I have been in some doubt with respect to the 

 nature of the scale covering the winter-buds, but have 

 come to the conclusion that this scale consists of two 

 modified leaves, connate by their margins along the 

 median line of the posterior and anterior aspect of the 

 bud respectively. The following reasons seem to justify 

 this view : 



1. The scale in all the eleven species examined 

 burst along the posterior face, generally to the base. 

 Salixpyrifolia and S. reticulata are exceptions, inasmuch 

 as they generally split at first a little more than halfway 

 down. The swelling of the axis completes this operation 

 later on. 



2. There is sometimes a ridge on the posterior face 

 corresponding to the line of union, as in 8. alba and 

 8. cinerea. In S. cordata there is a wide shallow 

 groove at the same place. 



o. The anterior face during the expansion of the 

 buds in spring becomes emarginate, bidentate, or more 

 or less deeply bifid at the upper end. S. alba and 

 S. luoida are exceptions, inasmuch as the anterior face 

 remains entire. I have observed no ridge, indicating 

 union, on the anterior face ; but as this is generally 

 absent or inconspicuous on the posterior face, it does 

 not much invalidate the presumed cohesion of the 

 anterior edges of the leaves. 



