226 Dr. C. Shearer. On the Oxidation Processes of 



in a watery suspension consumes considerable oxygen in the presence of iron 

 salts. The egg of the sea-urchin contains considerable quantities of this 

 lipoid. 



Warburg (13) has pointed out that there are many points in which the meta- 

 bolism of the fertilised egg resembles that of the yeast cell. In each it has 

 been shown that structure plays a very important part, as acetone prepara- 

 tions of both the egg and the yeast-cell retain considerable respiratory power. 

 Meyerhof (14) finds, however, that if acetone yeast is well washed with water, 

 it soon loses its capacity to take up oxygen. If a little watery extract of yeast 

 is added to the washed yeast, it immediately regains its lost respiratory 

 power. In the water used in washing the yeast Meyerhof found the presence 

 of some compound containing the (SH) group. Hopkins (15) has recently 

 isolated from the yeast cell a substance which is undoubtedly closely related, 

 if not identical with this respiratory body of Meyerhof. It proves to be a 

 combination of two amino-acids, glutamic acid and cystine, to which Hopkins 

 has given the name of glutathione. This dipeptide possesses most remark- 

 able properties in that, in the reduced (SH) form, it can take up molecular 

 oxygen, while in the oxidised (S-S) form so produced it can act as a 

 hydrogen acceptor, and can catalyse oxidations of the Wieland type, in 

 which no activation of oxygen probably takes place, but an activation of 

 hydrogen occurs instead. In the presence of a suitable acceptor the 

 hydrogen is removed and the oxidation of the original substance takes place. 

 It can therefore be both reduced and oxidised under the influence of factors 

 known to be present in the tissues themselves. Moreover, it possesses' 

 precisely those properties which a co-ferment adapted to an oxidase system 

 would possess, and at present stands entirely in a class by itself. Hopkins 

 has shown that it is present in most living cells, but he could find no trace of 

 it in the hen's egg, although it was very obviously present in the 30-hour chick.. 



I find, however, that in the ripe eggs and sperm of E. miliaris it is invari- 

 ably present in an appreciable quantity in the reduced form, but one minute 

 after fertilisation the same eggs give a very deep magenta colour by the nitro- 

 prusside test. It is very readily washed out of the eggs by warming them 

 with a trace of acetic acid in sea-water : the washed eggs then no longer give 

 the test. In the unripe egg, in which the nucleus is plainly visible, I could 

 find no trace of its presence by the nitro-prusside test. In the ripe eggs it is- 

 present in the reduced form in very variable quantities, no two females giving 

 the same result, probably depending on varying degrees of ripeness of their 

 gonads. In a number of samples of ripe sperm it seemed to be present in 

 much less quantity than in the eggs ; but here again in two samples of sperm, 

 it was present in much greater quantity than in any of the eggs examined. 



