OXIDATION AND REDUCTION 591 



presence of a mechanism which makes use of their energy in the actual progress of 

 the reaction. 



Further than this it is scarcely possible to go in the present state of knowledge. 

 A few further facts, nevertheless, are of interest. 



Permeability. Although acetone produces no visible change in the eggs of the 

 sea urchin, it renders the cell membrane permeable to electrolytes. A living egg 

 placed in distilled water rapidly bursts, after swelling up. Acetone eggs, after 

 soaking in sea water, undergo no change of volume in distilled water. 



Effect of Nucleus. Although blood corpuscles containing nuclei consume more 

 oxygen than non-nucleated ones, the fact does not necessarily imply that it is the 

 nucleus alone that is responsible. There is more protoplasmic material in the 

 former kind of cells. Certain evidence, also, shows that fragments of protoplasm, 

 free from nuclei, consume oxygen. The nucleus, in fact, counts as a part of the cell 

 structure. If red blood corpuscles of birds be frozen and thawed, cytolysis 

 occurs, the membrane is ruptured and certain cell constituents escape. It has 

 been shown by Warburg (1914, p. 322) that some of the structural parts are not 

 disintegrated, but, being insoluble, can be centrifuged off. By this process, we 

 obtain an upper layer of structureless qell substance and a lower one of structural 

 elements. When separated, and their oxygen consumption tested, it is found that 

 this is scarcely to be detected in the upper structureless layer, but in the lower 

 layer it is practically identical with that of the mixture before it is centrifuged. 



Effect of Increase of Structural Differentiation. The comparison of the oxygen 

 consumption of the fertilised egg of the sea urchin with that of the unfertilised 

 egg gave Warburg (1908 and 1910) opportunity to study this factor. The 

 increase is considerable, but not directly proportional to the number of new 

 nuclei formed. The change from one nucleus to a thousand, for example, only 

 causes a threefold increase in oxygen consumption. This fact indicates that the 

 " structure " in question is not the visible one of nuclei, and so on. A remarkable 

 fact, however, is that, if the eggs are cytolysed by placing in distilled water, and 

 shaking, the resulting suspension of apparently structureless debris consumed as 

 much oxygen as the normal cells in the case of the unfertilised . eggs ; but it was 

 reduced to one-tenth in the fertilised, dividing eggs, although the structure did not 

 appear to be so completely destroyed as in the former case. A significant fact, 

 which shows that the oxidation process, even in the unfertilised eggs, was not 

 normal after cytolysis, is that the carbon dioxide production ceased. 



Effect of the Cell Membrane. We have already referred to the fact that 

 changes of permeability occur in the act of fertilisation, and Warburg (1908) has 

 shown that, coincidently with this, the rate of oxygen consumption rises con- 

 siderably. Further, it was shown, as already mentioned (page 142), that alkali, 

 even when it does not enter the cell, causes a large rise in the oxygen consumption. 

 It is evident, then, that changes in the cell surface alone produce profound effects 

 on the cell mechanism, and further evidence is afforded that the " structures " 

 are of very minute character, since no obvious change takes place in the cell. 

 The minute nature of the protoplasmic elements was pointed out above (page 19). 

 The machinery can be put out of work, although no visible change may have 

 occurred. As if, in a petrol motor, the accumulator cells used for ignition were 

 discharged. 



Lillie states (1913) that the formation of indo-phenol blue by oxidation of a-naphthol and 

 dimethyl-paradiamino-benzene takes place most rapidly at the nuclear and cell membranes 

 of the frog's blood corpuscles. The passage of induction shocks is said to accelerate this 

 reaction, so that electrical polarisation of these surfaces is held to play a part. 



Effect of Cyanide. The action of potassium cyanide in extremely small 

 concentration is to stop all oxidation processes in cells, without doing any 

 permanent damage. Recovery can be obtained by washing away the cyanide. 

 This paralysis of oxidation has been referred to above (page 448) in relation to the 

 analysis of the muscle processes. The work of Weksacker (1912) on the heart of 

 the frog gives some interesting facts. We find, to take an example from his 

 table on p. 140, that a particular heart, in absence of cyanide, performed 1,180 

 g.-cm. of work with a consumption of oxygen corresponding to 23 mm. of 



