194 



MACROMOLECULAR COMPLEXES 



lipid is involved in defining the image of cytoplasmic membranes 

 and lamellae (see review by Sjostrand, 1959). 



It is clear that the chromatophore is not a rigid structure, for the 

 electron micrographs of shadowed preparations show that the chro- 

 matophore becomes a thin disk when it is dried upon a support. By 

 the same token, water accounts for a considerable fraction of the 



Fig. 8. A simple illustration of several factors which determine the image 

 of the sectioned chromatophore. If the cortex were opaque, the effect of geom- 

 etry and depth of focus could produce an apparent cortical thickness of 70 A 

 for actual values between 25 and 60 A as the section thickness varied between 

 200 and 100 A. 



volume of the organelle. Since the chromatophore behaves and 

 "looks" like a vesicle, it is probable that most of the structural mate- 

 rials are concentrated in a cortical region. 



The properties of the chromatophore indicate that protein rather 

 than lipid is present at the surface; for example, the chromatophore 

 is hydrophilic, has an isoelectric point, and acts as an enzyme. In 

 addition, the distortion or denaturation of protein is a prerequisite 



