98 



PARENCHYMA. 



Parenchyma of the Leaf. — This is ii name applied to all 

 the rest of the leaf-blade after taking out the epidermis, the fibro- 

 vaseiilar bundles, and the hypodermal fibers. It presents three 

 forms, which are quite distinct : 



a. Cells containing chlorophyll and found in the leaves of all 

 grasses without exception. 



b. Cells without color inside, found in certain species only. 



c. The star shaped and brandling cells found in the air canals 

 of species (Fig. 10.) mon* or less aquatic. 



The chlorophyll-bearing parenchyma is of two sorts: 



a. Where the grains are rather large and comiDact. 



b. Where some of the chlorophyll is in the form of grains, and 

 some of it is diffused more or less like jelly. 



Where a part of the chlorophyll is more or less diffused, the 

 rest is in cells which form concentric cylinders, or the cylinders 

 may be open in one or two ])laces. 



FtG. 46.— Section of a blade o Jimitclomi Harvardli, showing soiiu' closeil and some 

 open cylinder.s of cells containing grains of chlorophyll.— (Sudworth.) 



Fra. 47.— Section of part of a blade of Simrtina utricta var., showing largo cells of 

 parenchyma destitute of chlorophyll; these aro situated above the flbro-vascular 

 bundles, and in the middle of the lobes wliicli extend upward. 1 x 34.— (Sudworth.) 



