MINUTE STRUCTURE OF LEAVES 



155 



Notice that the green coloring matter is not uniformly 

 distributed, but that it is collected into little particles 

 called chlorophyll bodies (Fig. 120, p). 



166. Woody Tissue in Leaves. The veins of leaves 

 consist of nbro-vascular bundles containing wood and 

 vessels much like those of the stem 

 of the plant. Indeed, these bundles 

 in the leaf are continuous with those 

 of the stem, and consist merely of 

 portions of the latter, looking f *-* 

 as if unraveled, which pass ; 

 outward and upward from the 

 stem into the leaf under 

 the name of leaf-traces. 

 These traverse the peti- 

 ole often in a somewhat 

 irregular fashion. 



EXPERIMENT XXVIII 



Passage of Water from 



v, spirally thickened cells 

 Stem tO Leaf. Place a of the vein ; .p, paren- 



freshly cut leafy shoot of some chyma-celis of the 



. . spongy interior of the 



plant with large thin leaves, leaf, with chlorophyll 



such as Hydrangea hortensia, J e n d g ies; n ' nucleated 



in eosin solution for a few 



minutes. As soon as the leaves show a decided reddening, pull 



some of them off and sketch the red stains on the scars thus made. 



What does this show? 



167, Experimental Study of Functions of Leaves. The 



most interesting and profitable way in which to find out 

 what work leaves do for the plant is by experimenting 

 upon them. Much that relates to the uses of leaves is 



FIG. 120. Termination 

 of a Vein in a Leaf. 

 (Magnified ahout 345 

 diameters.) 



