124 Moore : The study of winter buds 



less whorled arrangement about the meristematic point, an exact 

 enumeration of leaves and papillae is impossible from a study of 

 serial sections. There remains, then, an element of doubt as to 

 the number of leaves and leaf fundaments actually contained in 

 these buds. 



* 



In buds of Syringa vulgaris the inner bud scales so gradually 

 emerge into leaves that it is Impossible to differentiate between 

 them. In fact what appear to be bona Jide scales in the bud de- 

 velop into normal leaves as the buds unfold. These scars are 

 crowded more or less into the ring of true scale scars which in 

 part become obliterated by the growth of the stem. Any enumera- 

 tion of nodes, therefore, in the shoot of the preceding season is 

 untrustworthy as a criterion for the number of leaves contained in 



■ 



the winter bud. The microscopic sections are more satisfactory 



in that they admit of a detailed and minute study of the vegetative 



point. From these slides it is evident that the vegetative point 



exhibits a variation in ability to produce new leaves in addition to 



those already existing in the bud. It is believed, from a study of 



the slides, that buds, which early in the spring develop buds in 



the axils of the uppermost leaves, do not make new leaves at the 



apex of the growing point, but that buds in which these axillary 



growths are absent early in the growing season, continue to form 



new leaves (figures 12 and 13). A probable explanation lies in 



the assumption that the energy of growth is directed to the upper 



axillary buds rather than to the meristematic point of the bud. 



These cells soon cease to function and die, thus terminating the 



growth of the stem. It appears, then, that the leaf content of the 



bud of Syrbiga vulgaris may receive additions in the spring. 



These new leaves are few, one or two pairs at the most They 



never fully develop but shrivel away when the meristematic point 



ceases to function. 



There is evidence that, in the leaf buds o^ Salix fragilis and 

 Salix alba, the leaves are not all organized at the bcghining of 

 winten The nodes on primary shoots vary from seven to thirty- 

 six. The leaves found in any bud of these shoots do not exceed 

 thirteen In number plus one or two papillae; moreover, the very 

 nature of the growling end, with its continued production of closely 

 appressed leaves, seems to establish the conclusion that the leaf 

 content Is not complete in Salix at the beginning of winter. 



