Guilliermond - Atkinson — 190 — Cytoplasm 



can stain the cytoplasm in living cells. Nevertheless this staining 

 is only transitory and the dye moves from the cytoplasm into the 

 vacuole. It is only after the dye has been localized in the vacu- 

 oles that the cells are capable of growing and no staining other 

 than vital staining of the vacuoles is compatible with growth. 

 The hypothesis of Devaux seems to be confirmed by the works 

 of Genevois and Genaud, who have shown that absorption of 

 salts by cells occurs exclusively along the cellular and vacuolar 

 membranes. It is necessary, however, to make reservations in 

 regard to the absence of chemical affinities from the cytoplasm, 

 since it has been seen that certain stains may, under some con- 

 ditions, be retained by the cytoplasm (pp. 18, 142). It has often 

 been supposed that the vacuolar system is not a simple center of 

 accumulation of metabolic products but that it is at the same time 

 the seat of phenomena of hydrolysis and of synthesis. According 

 to Kedrowsky and Volkonsky, the vacuoles are the secretion ap- 

 paratus of the cell and the seat of enzymes, particularly of pro- 

 teases, but this view seems to be exaggerated. There is reason to 

 believe that in the chemical phenomena which take place in the 

 vacuole, it is the cytoplasm which plays the active role, the vacu- 

 ole having only a passive role. 



Let us add that Parat considers that in animal cells, methylene 

 blue is always reduced in the cytoplasm and in the chondriome 

 (rH <12), and that it is, on the contrary, re-oxidized by the vacu- 

 oles (rH <16), which does not seem to be true in plant cells. 

 Going back to the hypothesis of Robertson (p. 122), Parat thinks 

 that the pair : chondriome plus vacuole, presides over the synthesis 

 of proteins, which, according to Robertson, calls for a lipide phase 

 and an aqueous phase and thus gives a morphological basis for 

 this hypothesis. Parat considers further that the vacuome is the 

 crucible in which are completed the operations begun in the chon- 

 driome, but these points of view are very hypothetical and lack 

 a solid foundation. 



It has been seen that this hypothesis of Parat is no longer 

 tenable, now that it is demonstrated that the chondriosomes do 

 not of themselves have a reducing role, contrary to what had 

 been supposed, and that the vacuoles may in certain cases be just 

 as capable of reducing actions as the chondriosomes. 



