372 Annals New York Academy of Sciences 



waters (1932) play a much greater part in cell protoplasm than was formerly 

 believed. All future experiments must, therefore, take place under rigid control 

 of the culture conditions. Only in this way shall we discover protoplasmic 

 adaptation phenomena. 



We shall first have to consider the possible effects of changes of pH and the 

 nitrogen content of waters, the latter having a direct bearing on trophic condi- 

 tions enabling one to distinguish between autotrophic and heterotrophic algae 

 (Algeus, 1946; Fogg, 1953; Saubert, 1957). 



It seems obvious, finally, that the permeability and uptake of dissolved com- 

 pounds depends principally upon the structure of the protoplasm, so that one 

 can no longer think in terms of a specific filter system. Such hypothetical sys- 

 tems are, however, still accepted by some, although Seifriz (1936) has indicated 

 that the permeation of the whole protoplasm was responsible. 



The correctness of this concept was confirmed by later experiments (Chol- 

 noky, 1952a, 19526; Hofler, 1959). On this basis, it seems to me highly proba- 

 ble that the structure of the protoplasm (after obligatory or optional nutrition 

 of the algal cells) is subject to changes which are also necessarily manifest in 

 the uptake of stain molecules. As the protoplasm of the purely autotrophic 

 algae must be adapted to small molecules and even ions, its microstructure 

 must be very different from that of the nitrogen heterotrophic species, the 

 protoplasm of which can take up amino acids or even bigger molecules (protein 

 particles, amino acid groups). These differences in protoplasmic structure, 

 which are due to the nutritional requirements of the cell and must also be mani- 

 fest in the uptake and storage of such substances as stains, seem to me so prob- 

 able that I am presently engaged in appropriate culture experiments. These 

 experiments will include the uptake of stains and fluorochromes in algae of the 

 same species which have been given different nutrients and also with algae 

 which are genotypically different for a study of their metabolism. 



Owing to circumstances beyond my control, these experiments have just be- 

 gun. It has, however, been supposed that the uptake of dissolved substances 

 represents an active function on the part of the protoplasm, i.e., that it must 

 be a dynamic process, and not one influenced by static structures such as lamel- 

 lae or filters. That is why it is hardly likely that the results of these experi- 

 ments will ever be reconcilable with the static concepts of such researchers as 

 Frey-Wyssling (1955). Electron microscopical observations cannot be re- 

 garded as a basis of research on the living substances concerned with the uptake 

 of dissolved molecules that Frey-Wyssling called "Grundplasma". 



I would like to recall what I said when I referred to the classical period of 

 cytology. The fixing and staining procedures then used could not lead to a 

 knowledge of protoplasmic structure, let alone changes due to physiological 

 causes. Electron microscopy must of necessity use similar, if more refined, 

 methods, as it is technically impossible to study living protoplasm with this 

 kind of microscope. The images obtained with the electron microscope are 

 only of static structural elements, and not of dynamic functions and changes in 

 the protoplasm. More succinctly, fixed protoplasm under the electron micro- 

 scope is at least partially an artificial product, as otherwise it would continue to 

 live unchanged. 



