74 



PHYSICAL ASPECTS OF MUSCLES 



Cross section 

 through I-band 



Cross section 



through end part 



of A-band 



Cross section 

 through H-band 



Fio. 34. A diagrammatic representation of the results of electron microscope 

 studies of sections through various parts of a striated muscle. From these 

 sections, the model given in Fig. 33 was deduced. 



Some of those working on muscle already feel that there is likely to be 

 something incorrect about the x-ray results, which showed no change 

 of configuration of the muscle proteins during a twitch. Clearly, much 

 remains to be done in this field. It is of particular interest to biophysi- 

 cists because, since the structural and chemical aspects have been reason- 

 ably established, it is likely that the essential missing features of muscles 

 will turn out to be encoded in some esoteric aspects of the physics of 

 molecules and their aggregates. These parts of biophysics belong to a 

 more advanced presentation than we can give here. 



