CELL STRUCTURE AND ENVIRONMENT 



B. J. Cholnoky 



Council for Scientific and Industrial Research, National Institute for Water 

 Research, Pretoria, South Africa 



During the so-called classical period of the study of cells, algal cells were 

 frequently used in cytological investigations. The great discoveries of Weis- 

 mann, Biitschli, Ramon y Cajal, and Flemming were made possible with fixed 

 and stained objects, but as the equipment and the microscopical methods then 

 available were unsuitable for living and especially for unstained objects, living 

 algal cells were only rarely used for cytological purposes. Listead, methods 

 were developed which were supposed to leave the fixed protoplasm unaltered, 

 and differential staining procedures were used which rendered visible to the 

 human eye structures which, it was believed, occurred in the living cell. Vio- 

 lent, but barely scientific controversy which often led to personal insults and 

 verbal battles ensued, during which the living cell was more and more for- 

 gotten. This was also due to the exemplary, or not so exemplary preparations 

 which were made to support sophisticated hypotheses which arose from staining 

 techniques. These techniques often resulted in works of art rather than 

 impressions of the living cell. 



No matter how perfectly fixation for specific purposes has been accomplished, 

 the living constituents of the cell must necessarily undergo alteration when 

 fixed (otherwise they would continue to live), and minute changes in the 

 protoplasm due to environmental factors cannot, therefore, be detected. The 

 difficulties were increased because colloidal physics had not yet been developed, 

 and because the changes were generally of a submicroscopical nature. Investi- 

 gations of these changes in the living protoplasm, therefore, were only later 

 tackled. 



Seen against this background, the accidental discovery by Benecke (1901) 

 of the reduction in size and the ultimate disappearance of the chromatophores 

 in Niizschia putrida (Synedra hyalina Provazek), by means of which he sought 

 to show a clear connexion between the size of the chromatophores and the 

 pollution (as he called it) of coastal waters, was surprising and also important. 



The approach adopted by Benecke was, however, soon abandoned, and the 

 observation of living algal cells continued only for the purpose of systematics 

 and morphology. The observed structures, cell components, etc., were re- 

 garded as something rigid and unchangeable, or, as we would express it today, 

 genotypically determined. Consequently, the results of these observations 

 were used only as characteristics: they were used, and frequently misused, for 

 describing species, and as a result, plant physiologists and the early ecologists 

 did not want to do anything with them. 



On the other hand, investigations into the causes of adaptation of algae have 

 begun. These investigations at first pursued a course which was of importance 

 to Man but not to the algae. Apart from the vague conjectures of the 19th 

 century, which were mainly concerned with descriptions of the habitat or with 

 plant geography, the first ecological study of algae was the so-called Saprobic 



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