LABORATORY STUDIES OF BUDS 23 



the stony particles. Each hair is a microscopic tube 

 (Fig. 27), out-growing from a surface cell, and serves to 

 conduct water and draw food materials into the tissues 

 of the root, whence they are conveyed to the leaves 

 above. 



27. Color. — The embryo in the seed is pale or color- 

 less. The seedling — except the root — is dark green, 

 after a short exposure to the light. Bat if the seedling 

 is thrown into strong alcohol, this newly acquired green 

 color is extracted, the coloring matter proving to be sepa- 

 rable from the leaves and stems, where it is generated. 

 It is a definite substance, to which the name Chlorojjh^U 

 has been given. Without this substance, plants cannot turn 

 mineral matters of soil and atmosphere into nourishment. 



III. LABORATORY STUDIES OF BUDS 



Buds appear as conspicuous features on most of the 

 perennial plants of temperate and cool climates, after the 

 autumnal fall of leaves. Such winter buds are to be 

 the subjects of the following studies.^ 



Exercise YII. The General Structure of Buds 



Buds of the following common species will show what winter buds 

 usually contain, in what a compact way the parts are pressed together, 

 and how some parts are shielded by others. 



Lilac. — View the bud endwise. AVhat is the arrangement of the 

 scales? How were the leaves arranged on the twig? 



Remove the scales and little leaves one after another, laying them 

 down in the order of removal. Xote a gradual change in the outlines. 

 From the last-removed members it is easy to see the morphology of 

 all the parts, including the scales. What are the scales? Cut a longi- 

 tudinal section. Use the lens. All parts are seen in position and 

 proper attachment. 



Draw : (1) An outer, a transitional, and an inner member, as taken 

 off (x 3.). (2) A longitudinal section (x 10). Label all parts. 



1 The parts of the leaf — blade, petiole, and stipules — should be 

 shown on the board to the class. 



