w 



/ 



..■■*^ 



-M 





r 



4fc..... , 





■^*'^(r^* 





# * 







^^* ^f 



Plate I. (cont.) The ultrastructure of plant cells. 



b. Electron micrograph showing the structure of cytoplasm in a mature cortical 

 cell located about 2mm from the tip of a maize (Zea mays) root. Fixation 

 with osmium in veronal buffer. The most prominent feature is the presence 

 of numerous large vesicles. The piasmaiemma seems to be continuous with 

 membranes surrounding the vesicles. Magnification, 36,000 ■, (Photograph 

 reproduced from Lund, Vatter and Hanson (1958) by courtesy of the authors). 



Key: N = nucleus; Va= vacuole; V= cytoplasmic vesicle (not clearly dis- 

 tinguishable in a); W = cellulose cell wall; PI = piasmaiemma; T = tonoplast 

 (not clearly distinguishable in b); Er = endoplasmic reticulum; g = small dense 

 granule (ribonucleoprotein particle). 



