TUMOURS 79 



lividus) and of Sabellaria alveolata. The eggs did not develop when the potential 

 was below about + 0-15 v. or above + 0-65 to 0*7 v. Ordinary sea-water had a 

 potential of + 0-25 v. Below E,j + 0-15 v. the development of the eggs was reversibly 

 arrested but above + 0-65 v. the cells were irreversibly damaged. 



Reiss (1931) has observed the slowing down of the cardiac rhythm of a marine 

 ascidian {Clavelina lepadifonnis Miill.) when the rH of the medium was reduced 

 below 20. 



Activation of eggs without sperm fertilisation leading to the initial stages of 

 artificial parthenogenesis has been reported by Brooks (1947) who finds that various 

 oxidation-reduction potential indicator dyes activated eggs of UrecJds cando and 

 Strongylocentrotus purpuratus in sea-water and suggests that there is a relationship 

 between the activating effect and oxidation-reduction potential of the dye. 



TUMOURS AND TISSUE CULTURES 



In an investigation of tissue cultures it was found that the growth of embryonic 

 chick heart tissue was, in general, the poorer the lower the electrode potential of 

 the culture medium. Mitosis and migration of cells had almost entirely ceased at 

 Ej, — 0-03 V. (Havard and Kendal, 1934). A regression of transplantable tumours 

 in rats and mice has been observed when methylene blue was injected into the tumour, 

 but not with certain other oxidation-reduction potential indicator dyes (Brooks, 

 1934.) Some observations have been made upon the effect of certain oxidation- 

 reduction potential indicators on the respiration and glycolysis of tumour and normal 

 tissues (Elliott and Baker, 1935). In low concentrations (1 in 100,000) the dyes 

 generally are able to stimulate respiration by virtue of their catalytic oxygen-carrying 

 effect. In higher concentrations (1 in 1,000) there is a distinction between the 

 behaviour of normal and tumour tissues. These stronger solutions of dyes inhibit 

 the oxygen uptake of slices of brain, testis, kidney and retina both in the presence 

 and absence of glucose. In the case of tumour tissue the dyes inhibit oxygen uptake 

 in the absence of glucose, but in the presence of glucose the oxygen uptake is 

 accelerated. With liver slices the oxygen uptake is accelerated in either the presence 

 or absence of glucose. Certain of the dyes investigated increase the aerobic glyco- 

 lysis of tumour slices and to a less extent of tissue slices. The electrode potential 

 and the chemical constitution of the dye are of importance in this respect. 



Among papers on the oxidation-reduction potential relationships of tissues are 

 the effect of dyes on tumour respiration, (Dickens) the potential in muscle, (Uchimura, 

 1937) the effect on neural growth (Waddington, Needham and Brachet, 1936) and 

 on skin (Kelley and Williams). 



YEAST PREPARATIONS 



It has already been stated in the previous section that yeast cells which have 

 been washed free from " metabolites " are no longer able to reduce dyes (Harden 

 and Norris, 1914) or effect the usual fall in electrode potential (Cannan, Cohen and 

 Clark, 1926). Addition of a suitable metabolite restores these activities of yeast 

 cells. Boyland (1930) found that addition of dyes, e.g., methylene blue, which 

 have an Eq^ value at pH 6-0 of — 0-05 v. to + 0-10 v. may accelerate yeast fermenta- 

 tion by acting as oxygen carriers. Lipmann (1934) found that in the presence of 



