18 THE BUILDING UP OF THE 



them, and contributing also to the growth of that portion 

 of the axis or stem which is beneath them, and to the in- 

 crease of the number of the rootlets in the soil. 



Each of these phytons or leaves developes also, more or 

 less perfectly, its own gemmule or young bud, which, un- 

 doubtedly, corresponds to the gemmule or bud formed by 

 the first leaf, the unfolding of which constitutes the growth 

 of the first season. But these new buds never come to any- 

 thing the first year, but retain their rudimentary condition 

 through the winter months, and appear as projecting points 

 on the outside of the shoot, after the leaves which formed 

 them have dropped from the stem. The gemmule or bud 

 formed by the first leaf, is the only one of the series which 

 developes the first season. 



As the heat and light of the sun decrease, the vital acti- 

 vity of the phytons or leaves diminishes, and the intervals 

 between them gradually cease to form, until at length the 

 elongation of the axis is wholly stopped. About this time 

 the current of sap is diverted away from the leaves to the 

 buds forming at the bottom of each leaf-stalk, and especial- 

 ly to the terminal bud which grows at the top of the shoot. 

 This attraction of the sap or formative material away from 

 the leaves by the newly-forming tissues of the buds, is un- 

 doubtedly one of the principal causes which produce their 

 decay and separation from the shoot. When the leaves 

 begin to change their color (the sure presage of their ap- 

 proaching fall), it is therefore an infallible indication that 

 the sap is being diverted away from them to the buds, 

 which have begun to grow, and that the shoot constructed 

 by their united labors is about to be prepared for winter. 



This preparation of the shoot for winter is effected by 

 the development of another set of leaves, which other 

 writers call bud-scales, but which I call [folia tegmentia) 

 covering or protecting leaves. It is not nutrition, but pro- 

 tection which is required by the shoot during winter, and 

 these leaves are organized expressly for this very purpose. 

 They contribute nothing whatever to the support of the plant, 

 but they shield it from the inclemency of the weather. It is 



