OXYGEN SUPPLY OF CERTAIN ANIMALS 307 



Such reactions in plants are explained by the presence of an 

 enzyme which builds up a peroxide from a contained compound 

 and the atmospheric oxygen. This peroxide, then, 'has its 

 oxygen removed by a peroxidase, in the atomic or active form, 

 and the atomic oxygen then oxidizes the color-producing com- 

 pound. It is possible that an enzyme complex similar to that 

 of plants exists in the chitin of the chironomid larvae. 



That two enzymes, or an enzyme and an enzyme-like substance, 

 are being dealt with is certain. For if a portion of the bruised 

 chitin be treated with guaiacum, a blue color results. If another 

 portion is raised to a temperature which is above the killing 

 point of the enzyme, namely, 56°, and again a part tested with 

 guaiacum, no color results. But if to the remaining heated 

 portion, guaiacum and hydrogen peroxide are added, the guai- 

 acum is at once oxidized to the blue color compound. These 

 results indicate that a true thermolabile enzyme builds up a 

 peroxide from which atomic oxygen is being split off by the 

 action of an enzyme-like substance which is not killed by boiling. 



A peculiarity exists here, however, in the fact that alcoholic 

 tincture of guaiacum is the only one of the indicators tried 

 which was oxidized by the reaction of this enzyme complex. 

 No reaction was obtained with benzidine, a-naphthol, or p-phenyl- 

 enediamine hydrochloride. It would be expected that active 

 oxygen would affect oxidation indiscriminately. Bertrand ('96) 

 showed that laccase acted upon hydroquinone and pyrogallol 

 with ease, but not upon resorcinol or phloroglucinol. Bayliss 

 ('14) seems to believe that there is a specificity here which "lies 

 in the peroxide component of the oxidase system. If this be so 

 it is possible that there is some intimate relationship necessary 

 between the structure of the peroxide and the substrate in order 

 that close connection may be possible, so that the active oxygen 

 may enter into the immediate union with the latter." Such a 

 close connection between the elements of the reaction may exist 

 in the case of the enzyme complex in the chironomid larvae, 

 which would account for the specificity shown. 



It would seem that there might be some relation between the 

 peculiar enzj-me-complex found in the chironomid larvae living 



