THE ANATOMY OF WOODY PLANTS 



Fig. i will make clear the organization of cells in an immature 

 seed pod or pericarp of an iris. Each element obviously consists 

 of a large central cavity as noted above, variously known as hydro- 

 plastid, hydroleucite, tonoplast, and vacuole. The last designa- 

 tion seems best for descriptive purposes. Surrounding the median 

 space, which in life contains water with various substances in 



solution, is the proto- 

 plasmic utricle. The 

 nature of the latter 

 varies in different 

 cells. In the ele- 

 ments to the left side 

 of the illustration the 

 protoplasm appears 

 as a somewhat 

 minutely granular 

 substance, while in 

 the cells to the right 

 the structural organi- 

 zation of the proto- 

 plasm is marked by 

 the presence of oval 

 bodies, the chloro- 

 plastids, which in life 

 color are green. A 

 dark body of larger 

 size is to be seen 



somewhere against the cell wall and imbedded in the protoplasm. 

 This is the nucleus, one of the most important organs of the cell, 

 which appears to preside over all its changes and activities. 

 Another body, generally larger and lighter than the nucleus, is 

 frequently present in the cells under discussion the oilplastid 

 or eleoplast. This is conspicuously spongy in its structure. We 

 may now turn with advantage to the organization of the cell 

 wall. On the left side of the illustration the common outer wall 

 is limited by a distinct membrane, the cuticle, which is chemically 

 different from the rest of the wall substance and is viable to 



FIG. i. Transverse section of young pericarp of 

 Iris species, showing organization of cells of epidermal 

 and fundamental tissues. 



