306 ARCH E. COLE 



But obviously a peroxidase or any other catalyzing agent is 

 of no use as an oxidizing agent without the pressure of a peroxide 

 from which the oxygen ma}^ be split off. There are no peroxides 

 in the blood of the chironomid larvae, otherwise guaiacum would 

 be oxidized upon its addition. Neither were peroxides found 

 in the extract of the soft tissues of the body. 



However, the chironomid larvae contains a true enzyme 

 whose reactions are quite different from the non-thermolabile 

 enzyme just discussed. During the experiments on the larvae 

 there were at times found to be small particles in the aqueous 

 extract of the tissues which gave the blue color with tincture of 

 guaiacum before the hydrogen peroxide was added. This matter 

 was further investigated, and it w^as found by careful dissection 

 and testing of various parts of the larvae that the reaction w^as 

 only given by the chitin. Only the inner surface of the chitin 

 was involved and the action was more pronounced when the 

 chitin was thoroughly bruised or macerated. The separation 

 of the chitin from the body tissues was accomplished by slitting 

 the larvae longitudinally and scraping the organs out. This treat- 

 ment removed the hypodermal cells which secreted the chitin. 

 Then by grinding the chitin slightly in water with a pestle and 

 adding the guaiacum, the blue color gradually appeared. This 

 color is at first confined only to the inner surface of the chitin, 

 but after a time gradually diffuses into the surrounding medium. 



Tests showed that this reaction in the chitin is dependent 

 upon an enzyme which is killed at a temperature of about 56°C. 

 It was also found that if the extract was allowed to stand for 

 some time before the guaiacum was added, the reaction was 

 weakened". Standing for a period of twenty minutes greatly 

 decreased the intensity, and if the extract remained for thirty 

 minutes before the guaiacum was added, the reaction was barely 

 if at all perceptible. The presence of such an enzyme in animals 

 is quite unique. Generally a peroxide must be added to an ani- 

 mal extract before it will oxidize guaiacum. 



In plant tissues such enzymatic reactions are very common. 

 In apples, for example, a cut surface immediately oxidizes 

 guaiacum, or if left by itself will turn brown, due to the oxidation 

 of a chromogen compound which is brown when oxidized. 



