I. 



T 



4 



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STRUCTURE AND CONTENTS OF TERMINAL 



BUDS. 



The terminal buds seem the most natural place to begin 

 the consideration of the subject before us. In a general way, 

 in the introductory notes, the structure of these buds, situated 

 at the ends of shoots, has been pointed out, and it is for us 

 now to pass more deeply into the subject, and with the aid 

 of the microscope determine the minute anatomy of these 

 points of conservation of vital energy. As before said, the 

 leading component parts are the overlapping bud-scales pro- 

 vided with more or less hair and varnish, within which is 

 the bud proper, that is, the incipient shoot, bearing its leaves 

 as minute outgrowths which are arranged in a definite (acrope- 

 tal) order; the large outer ones inclose the younger and 

 smaller ones, the central point of all being the extremity T 



of the stem. As In all newly formed vegetable tissue en- ' c 



dowed with the subtile power of further growth, the cells 

 that compose the central portion are small, thin-walled, 

 and their contents consist largely of that colorless semi-fluid 

 and extremely variable substance called protoplasm, the ac- 

 knowledged vehicle of vital activities. Below this cone of 

 delicate and almost homogeneous cellular tissue the stem is 

 seen to take its origin with the differentiation into the cylin- 

 der of wood cells and vessels, having upon its inner side the 

 comparatively unchanged pith, and, without, a thin layer of 

 active cells that is to continue the growth in size of the 

 branch by developing upon its inner surface new layers of 

 wood, while outside is produced a protective substance famil- 

 iarly known as bark. Therefore, by mentally combining 

 transverse and longitudinal sections of the base of a terminal 

 bud, the observer is able to determine the method of forma- 

 tion of the various elements that go to make up an ordinary 

 twig. The young leaves that arc a part of the dormant bud 

 while still very small present but little more than the simple 

 cellular condition common to the short tip of the branch that 

 bears them. Among the outermost it is possible to distin- 

 guish the details of form and outline, together with the vena- 

 tion and other points of differentiation determined by a micro- 

 scopic examination of newly unfolded leaves. Of course, the 



