l84 FINE-STRUCTURE OF PROTOPLASM 



II 



its original morphological meaning proposed by Reinke (i88r), 

 Zacharias (1883), Berthold (1886) and others. 



Cytological morphology needs collective concepts such as lignin, 

 chromatin, lipids and plastin, which do not designate well-defined 

 chemical compounds but classes of substances which are defined in 

 a morphological sense as microscopic phenomena. If these concepts, 

 created by the microscopist, are not satisfactory from a chemical point 

 of view, chemistry should provide a new and more suitable termi- 

 nology. In fact, microscopic microchemistry, adjusted to morphology, 

 can never satisfy the high demands of an exact chemical and structural 

 description. 



Bensley has succeeded in giving a closer characterization of the 

 structural proteins of the liver (1938, 1943). The mobile proteins are 

 soluble in 0.8 5 % NaCl. On further treatment with N/200 NH4OH the 

 mitochondria and the nucleochromatin are dissolved. From the re- 

 mainder a homogeneous substance, plasmosin, can be extracted with 

 NaCl 10%. This is described as a gel- and fibre-forming constituent 

 of the protoplasm (Bensley, 1938). The protein ellipsin is left, and 

 Bensley compares it with Reinke's plastin. Plasmosin is compared 

 with the muscular protein myosin (Bensley, 1943); according to 

 Mirsky and Pollister (1945), however, it has its origin in the 

 nucleus and should be regarded as a nucleoprotein. 



Criticism of the tbeo'j of junctions. The submicroscopic reticular 

 structure of the cytoplasm has been decidedly rejected by Hofler 

 (1940). In his investigations on cap-plasmolysis (compare Fig. 114, 

 p. 197) he succeeded in making the cytoplasm of Allium cells swell 

 up to 10 and more times its original volume with the aid of alkali salts, 

 without causing the cells to die. Hofler concludes that no framework 

 can be present, for the enormous swelling has pushed the structural 

 elements so far apart that they must completely change their mutual 

 relations and positions. This reasoning would be correct if only 

 granular particles were operative in the cytoplasm. It has been pointed 

 out, however, that a submicroscopic or even molecular framework 

 can attain enormous degrees of swelling without breaking down its 

 structure (see p. 67). It seems to me, therefore, that Hofler's inter- 

 esting observations are in favour of the theory of junctions rather than 

 against it, for what system other than a gel could be inflated ten-fold 

 without losing its inner organization? That the latter has been pre- 



