156 



H. J. Arnott 



(as many as 15 or more pairs may be present in one cell) extending from the peri- 

 pheral cytoplasm into the vacuole (Fig. 2). The chambers arise by successive changes 

 in the membranes (Fig. 2). When the paired membranes are cut transverse to the long 





N 



■ i^ 



Fig. 4. Tr.inscction of styloid idioblast of Eichbornia crassipes. Fixation KMnOj poststained 



axis of the cell, a series of hourglass profiles can be seen. By densification at the center 

 of the hourglass profile the crystal chambers develop in a linear sequence (Fig. 2). The 

 growing chambers often show rounded contours but later they become rectangular in 

 transverse section. The electron-dense loaded chambers, at an intermediate stage in 



