364 



CHLOROPLASTS AND CHROMOPLASTS 



CHAP. 14 



The results obtained by microphotography in the ultraviolet were 

 confirmed by the electron microscope observations of Kausche and 

 Ruska (1940), shown in figure 42. The thin discs or laminae revealed 

 by this photograph vary in diameter from 0.4-2.5 n, that is, they are of 

 the same size as, or larger than, the grana — but their thickness is only 



Fig. 43. — Portion of a chloroplast of Elodea canadensis, showing units (after 

 Roberts 19422).* Inset, X 10,000; main figure, X 100,000. 



* Thanks are due to the Radio Corporation of America for use of the electron 

 microscope and to Miss Nina Zworykin for taking this electron micrograph. 



