368 Annals New York Academy of Sciences 



Thus, the causes of adaptation to the conditions of brackish water, i.e., the 

 considerable variation of osmotic pressure, were to be found in plasmolysis 

 which must necessarily and at least temporarily occur. 



The experiments which were undertaken (Cholnoky, 1928a, 19306, 1932) 

 showed that apart from certain fundamental morphological features which 

 seem to be genotypically determined, and which are characteristic for the 

 various algal groups during plasmolysis, there are large morphological differ- 

 ences between the plasmolyses of freshwater and brackish water species. 

 Among other things, the distribution of viscosity of the protoplasmic colloids 

 is characteristic for the species. It was ecjually evident that the brackish water 

 species poses a high degree of permeabihty in regard to the salts in solution 

 in their habitat. In Hungary the high degree of permeability is confined to 

 the carbonates, and only to a lesser degree to the chlorides, although the cells 

 show only slight or nonpermeability to such plasmolytica as nitrates, sugar, 

 urea, etc. The same species when found along the South African coast are 

 mostly permeable to the chlorides, whereas when they occur in the South 

 African sodium carbonate rich waters of the Jakkals River for instance, the 

 same permeability to carbonates as in Hungary was observed. 



These observations forced me to the conclusion that owing to the high degree 

 of permeability of the protoplasts, the brackish water species are ecologically 

 favored. It follows that if such an assumption were true, there would be far- 

 reaching colloid-physical effects. The permeating salt molecules would, under 

 normal circumstances, alter the electrical charge of the mono- or polymolecular 

 micelles and thus be the cause of coacervation and ensuing coagulation and 

 death. The protoplasm of brackish water species appears to be extremely well 

 protected against such alterations of electrical charge, and further study will 

 probably provide important information on the submicroscopical structure of 

 the protoplasm. 



Typical freshwater algae which were treated with a plasmolyticum consisting 

 of some partly evaporated brackish water from another habitat speedily died 

 as a result of permeation (Cholnoky, 19306, 1931<z, 19316). Others, however, 

 remained plasmolysed for an extraordinarily long time without showing any 

 sign of protoplasmatic damage and without the least trace of permeation. 

 Other chemical compounds for which the protoplasts of the investigated species 

 were more or less permeable, acted immediately on permeation as poisons, 

 during which it was seen that the gradual destruction of the protoplasm indi- 

 cated an unecjual resistance of the protoplasmic components of the cell (Chol- 

 noky, 1953). 



Hofler (1951) obtained similar results and found that Na2C03 acted in a 

 specific manner on the diverse species of bog algae (Desmidiales). The cells 

 of some species were slightly permeable, others were barely permeable. The 

 nonpermeable ones were able to survive plasmolysis lasting several days with- 

 out sustaining any visible protoplasmatic damage. (It was possible com- 

 pletely to deplasmoly.se Euastrum after pla.smolysis lasting 72 hours.) I was 

 able to confirm that certain brackish water algae were even more resistent to 

 plasmolysis than Euastrum. These species built a superficial inner cell wall 

 on the site of positive plasmolysis; i.e., at those places where the protoplasm 

 body had withdrawn from the original cell wall. As a result of the possible 



