Guiriiermond - Atkinson — 38 — Cytoplasm 



results obtained by these different methods, that of micro-injection 

 excepted, are very divergent and have resulted in pB. values rang- 

 ing from 3.4-5 to 7.8, whereas, according to Vles and Reiss, as 

 well as according to Small, the pH is 5.1-6.2. There is reason to 

 wonder as to what is the value of results obtained by these methods. 

 First, no value can be placed on results obtained from plant juices 

 since they do not express the pR of living protoplasm, but only 

 inform us concerning that of the vacuolar sap, more or less strongly 

 modified by the treatment. One can not deny, furthermore, that 

 the other processes, that of Vli^s in particular, offer great disad- 

 vantages because the crushing practiced on living cells, no matter 

 how rapidly executed, does cause injuries and these lead rapidly to 

 the death of the protoplasm. It seems evident that protoplasm be- 

 comes acid immediately after death. 



In addition, and this is the real objection, none of these pro- 

 cesses allows the total pH value of the protoplasm to be obtained 

 without regard to the parts which make it up. Now, among these 

 parts the vacuoles must be considered. As will be seen, they give a 

 clearly acid reaction. It follows that the results obtained have 

 no value, for they are only the pK value of the cytoplasm and vacu- 

 oles combined, and are obtained, usually, after the death of the 

 cells. 



More precise results obtained by micro-injection, with the aid of 

 Chamber's micromanipulator and Clark indicators, have given a pH 

 value neighboring on neutrality: about 7 — from 6.8-7.2 (D. and J. 

 Needham, Rapkine and Wurmser). It is suspected, moreover, 

 that micro-injection itself can induce disturbances in the cell and 

 modify the reaction of protoplasm. The ideal would be to measure 

 the cellular pH by means of vital dyes. Unfortunately the Clark 

 fndicators do not ordinarily penetrate the cells and are all of them 

 more or less toxic. 



Cellular rH:- It is possible to measure directly the cellular rH in 

 accordance with the oxidation state (colored) or reduction state 

 (uncolored) taken on by the dye in the cellular medium. This is 

 accomplished by micro-injection into the cells of oxidation-reduction 

 indicators. The rH value given by cells in the presence of air varies 

 from 12 to 14. The rH value of the same cells measured after an 

 anaerobic period is in the neighborhood of 7 (Brooks in Valonia, 

 Wurmser and Rapkine in Spirogyra) . The micro-injection method 

 has the disadvantage of injuring the cell and of introducing indi- 

 cators which are generally toxic. The use of vital dyes appears to 

 be the best method. It is unfortunate that these accumulate almost 

 entirely in the vacuoles and generally produce only sublethal stain- 

 ing of the cytoplasm. However, with Gautheret, we have used 

 Janus green. In yeasts, particularly in Saccharomyces cerevisiae, 

 this dye is taken up by the cytoplasm and is rapidly reduced there 

 to its rose derivative, which does not revert to its green form. If 

 the medium contains nutrients, the dye is excreted to the exterior 

 in the form of the rose derivative. If these nutrients are composed 



