Guillierixiond - Atkinson — 18 — Cytoplasm 



cytoplasm of living cells, but these dyes traverse the cytoplasm 

 without coloring it and accumulate exclusively in the vacuoles. They 

 stain the vacuoles only in the living state and disappear in them 

 with the death of the cells, reappearing in the cytoplasm and the 

 nucleus. They will be discussed later (p. 131) in connection with 

 the vacuoles. Some of these dyes, however, such as Nile blue and 

 methylene blue, can at the same time produce diifuse staining of 

 the cytoplasm, especially when used at a high pH. 



It is shown today, by the work of KtJSTER, confirmed by ours in 

 collaboration with Gautheret, that, although some dyes never 

 pass through the ectoplasmic layer, without any reason for this 

 being evident, many others can more or less easily penetrate living 

 cells. Basic dyes are in general the only ones which penetrate the 

 cell. Like those already mentioned, they may accumulate exclu- 

 sively in the vacuoles under certain special conditions or else may 

 show a predilection for the chondriosomes which they stain first. 

 Most of these dyes end by staining the cytoplasm and the nucleus 

 a little before the death of the cell. Among these dyes, chrysoidine 

 stains the cytoplasm and nucleus superbly in cells which are unques- 

 tionably alive, clearly showing cytoplasmic currents. This is with- 

 out doubt explained by the nature of this dye which is readily 

 dissolved in lipides. 



The acid dyes in general do not penetrate living cells. Eosine 

 and erythrosine, however, may color the living cytoplasm and 

 nucleus as Kuster has shown. But these dyes, incorrectly con- 

 sidered by this observer as the best suited to staining of the cyto- 

 plasm, penetrate living cells only with great difficulty and only a 

 short time before the death of the cells, without doubt because of a 

 modification of permeability produced at that moment. Aurantia, 

 another acid dye, penetrates living cells very slowly but immedi- 

 ately kills them. 



It should be noted that all dyes capable of producing vital 

 staining of the cytoplasm do so only between slide and cover glass, 

 therefore in cells placed under defective conditions, and it may be 

 admitted that this is sublethal staining, i.e., staining which occurs 

 only in the period which precedes the death of the cells. 



If plants are cultivated aseptically in media to which these dyes 

 have been added, it is noted that the plants grow but no coloration 

 of the cytoplasm is produced. The stains accumulate in the vacu- 

 oles. It is only in cells where growth has stopped that the cyto- 

 plasm, nucleus and chondriosomes may show staining. 



Chrysoidine, for example, which so easily stains the cytoplasm 

 and nucleus in cells placed between slide and cover glass, accurnu- 

 lates only in the vacuoles in plants cultivated in a medium to which 

 this dye has been added, and is scarcely taken up by the cytoplasm 

 except in cells where growth has stopped. Recent research (GuiL- 

 LiERMOND and Gautheret) makes it possible to explain this differ- 

 ence in behavior. The staining of the cytoplasm between slide and 

 cover glass is, in reality, obtained under abnormal conditions and 

 usually with toxic quantities of the dye. This is, therefore, unques- 



