THE CELL AS A PHYSICO-CHEMICAL UNIT 



There is comparatively little information about the 

 details of structure, and so forth, of these gels in most 

 cells. In striated muscle cells, the gels become so pro- 

 minent as to be the characteristic feature of the cell, and 

 it is known that the component molecules are arranged 

 in organised fashion to produce definite intracellular 

 bands, discs, fibres and membranes. The most striking 

 of these features of the living cell is the distinction be- 



Olycogen 



Myosin 

 nisofropic band 



~7 



Isotropic band 

 A.T.P 



Nucleus 



Alkaline phosphatase 

 Acid phosphatase 

 Deoxypentose nucleic acid 

 Pentose nucleic acid 



Fig. 2. Diagram of distribution of substances in a striated muscle fibre 



tween anisotropic bands, which presumably contain the 

 greater part of the myosin of the cells, and the isotropic 

 bands. The former bands rotate the plane of polarisation 

 of plane polarised light, whereas the isotropic bands do 

 not. Cytochemical studies on muscle cells are at present 

 rather scanty. It is known that adenosine triphosphate 

 is concentrated in the isotropic bands, and that these 

 bands also contain a relatively labile alkaline phospha- 

 tase. Whereas acetone resistant acid phosphatase and 

 desoxyribose nucleic acid are both mainly present in the 



