72 OTTO GLASER. 



tirely absent in a " neutral " oil ; is, moreover, constantly being 

 produced; and, as constantly oxidized to dioxystearic and, very 

 likely, other lower fatty acids. The differences between the digests 

 and the controls, however, remain significant. 



IV. 



By far the most fruitful observation was made, not on the di- 

 gests themselves, but on the litmus which in certain cases was used 

 as the indicator. As compared with the controls in sea-water and 

 oil, and in exudate without oil, neutral litmus, when shaken up in 

 mixtures of secretion and either whale oil or olive, instantly be- 

 comes pinker. After two hours the pink is distinctly intensified, 

 and after twelve, such digests stand out sharply from their controls. 



Within twenty-four hours all color, including the pink, disap- 

 pears in the oil-secretion digests. If more litmus is now added, it 

 again turns pink, and, in the course of time, fades out completely. 

 The controls, on the other hand, even after forty-eight hours, still 

 appear "neutral," with perhaps only the faintest leaning toward 

 pink. 



It is plain that the litmus is not functioning here as a direct 

 indicator of acidity. Very likely the change to pink and the final 

 complete decolorization are the first and last visible steps in a 

 process of reduction. But why, we may ask, the difference be- 

 tween the secretion digests with neutral oil and the controls? If 

 the explanation is to be found in the superior reducing powers of 

 the oil-secretion systems, then these must be producing a substance 

 capable of binding oxygen. Moreover, they must be producing 

 this material at a rate far in excess of the rate in the controls. 



Now, if the oils in the presence of secretion are undergoing 

 ordinary lipolytic cleavage, one of the reaction products must be 

 oleic acid, and this, as is well known, absorbs oxygen with great 

 ease. Is it possible, then, to attribute the decolorization of the 

 litmus to the reducing powers of oleic acid? We can only do this 

 if we can first show that oleic acid is present in higher concentra- 

 tion in the digests than in the controls; and, if we succeed in prov- 

 ing this, we shall incidentally also furnish the proof that the only 

 source of oleic acid the neutral oil is undergoing accelerated 

 hydrolysis in the presence of egg-secretion. 



