ELECTRON MICROSCOPY 



1723 



mean that in the natural state chloroplasts do not have a membrane ; but 

 merely that it has not yet been possible to demonstrate its existence. 



A second type of thin structiu'e, repeatedly observed in electron micro- 

 graphs of disintegrated chloroplasts, are small round discs, with a diameter 



^•■??^;i 



Fig. :i7A.8. Electron micrograph of a maize granum that has 

 become dissociated into discs (after Vatter 1952). 



Fig. oT.V.'j. LlttLiuii iiiiiiugiapli^ bowing the uul-.ijlded blebs 

 that surrounded a maize chloroplast isolated in distilled water and 

 then dried (after Vatter 1952). Compare with fig. 37A.5. 



about equal to that of a single granum. They often appear in groups of 15 

 to 50, looking like a scattered money roll. These rolls are very clearly 

 visible in pictures of maize chloroplasts taken by Vatter (1952), of which 

 fig. 37A.8 is a good example, but were first noted by Frey-Wyssling and 

 Muhlethaler, (1949), who used tobacco leaves. Frey-Wyssling interpreted 

 them as protein lamellae, which he assumed to be stacked in the intact 

 granum, like layers in a cake, held together by interlarded layers of 



V_ 



