I40 



FINE-STRUCTURE OF PROTOPLASM 



II 



shows clearly how opportunities of entering into the protoplasm 

 multiply as the lipids become more hydrophilic in character. 



Chemical composition of the cytoplasm. The proportions of the com- 

 pounds described above vary considerably in the cytoplasm (Table 

 XrV). This is especially so for lipids, carbohydrates and water-soluble 

 compounds. Although the two analyses in Table XIV represent ex- 

 treme cases, it is evident that protein is the main constituent of the 

 cytoplasm. Only small amounts of the other constituents are structural 

 compounds. In the cytoplasm of the sUme mould Reticularia there are 

 considerable quantities of reserve substances such as carbohydrates, 

 soluble nitrogenous compounds and probably most of the lipids. 

 Whereas slime moulds can be dried and analysed without difficulty, 

 the cytoplasm of tissues with solid cell walls can not. In this case the 

 membranes have to be broken in a blendor and the cell contents sus- 

 pended in an appropriate solution, from which the constituents of 

 the cell wall, the cytoplasm, the plastids and the nucleus must be 

 separated by centrifuging and by fractionated salting out, e.g. with 

 ammonium sulphate (Menke, 1938a). The fraction corresponding to 

 the cytoplasm yields the analysis recorded in the right column of 

 Table XIV. By this method of preparation, all water-soluble com- 



TABLE XIV 



CHEMICAL COMPOSITION OF CYTOPLASM 



Plasmodium 

 ReticuLria Ijcoperdon 



KlESEL 1930, p. 257 



Leaves 



Spinacia okracea 



Menke 1938a, p. 289 



Proteins 



Soluble N-compounds. 



Lipids 



Phosphatides 



Cholesterol 



Nucleic acids 



Carbohydrates . . . . 



Ash 



Unknown 



29.07 

 12.00 



19.05 



4.67 



0.58 



5.68 



25.08 



5.87 



100.00 



0/ 



o 



85.0 



0.7 



3-1 

 II. 2 



1 00.0 



