628 THE RESPIRATION AND [pt. iii 



myself using micro-injection methods (see p. 845) confirmed this 

 observation of Warburg's, and showed that echinoderm eggs could 

 remain for 3 hours in sea water at pH 6-o (normal 8-4) without 

 undergoing any change in the intracellular pH. 



Runnstrom in 1929 re-opened the question of the influence of/)H 

 on echinoderm egg respiration. Like Warburg, he found that the 

 more acid the/>H the less intense the respiration; thus at/>H 6-5 the 

 inhibition was 27 per cent, and at pH. 6-1 51 to 58 per cent. This 

 effect was equally shown by fertilised and unfertilised eggs. Runn- 

 strom remarked that the difference between the pH of the cell- 

 interior (6-6, Needham & Needham) and that of the sea (8-4) 

 appears to be necessary for normal respiration. 



Another powerful agent which influences the respiration of these 

 eggs is methylene blue, according to the work of Barron. Addition 

 of this dye to the vessels in which the eggs are respiring much in- 

 creases the rate at which they do so. The effect is shown, indeed, 

 by any reversibly oxidisable dye, and Barron & Hoffmann have 

 studied the action of the rH indicators (see p. 866) on egg-respiration. 

 It depends (a) on the rH of the dye, (b) on the permeability of the 

 cell. If the dye is positive to the cell the effect is maximal, and 

 decreases with increasing negativity, for in order to bring about a 

 raised respiration the rate of reduction of the dye must exceed the 

 normal rate of oxygen-consumption of the cell. Here the dye is acting 

 as an additional "Atmungsferment " and probably oxidising cyto- 

 chrome. With methylene blue, the effect is not found, according to 

 Runnstrom, in the case of fertilised eggs. 



As a result of his experiments Warburg suggested that the toxicity 

 of various salts for echinoderm eggs was due to their effect upon the 

 oxidations going on in them. Thus he found that the poisonous action 

 of sodium chloride solutions could be abolished by adding a trace 

 of sodium cyanide to them, so that an agent which prevented the 

 great rise in respiratory rate acted as a detoxicant. Other examples 

 of neutraUsed effects could be obtained with calcium, magnesium 

 and potassium chlorides, etc., where it was found that the nearer 

 to normal the respiratory rate was kept the less poisonous the solu- 

 tions were, and the higher percentage of normal developing embryos 

 occurred. From the same standpoint, the influence of extremely 

 small quantities of gold, silver and copper ions was studied. These 

 might raise the respiratory rate by as much as 63 per cent. But their 



