103 



The Nature of the Investigation 



The object of our experiments may be formally stated as 

 follows : 



{a) To study the distribution of the oxidases and of catalase 

 in the higher plants, beginning with the lowest; using repre- 

 sentatives of as many available orders and families as possible. 

 To make the data more systematic and to reveal, if possible, any 

 natural relationships, the results are tabulated according to the 

 botanical classification.^^ 



{b) To examine as many plant parts as possible, to see if there 

 is a localization of the oxidases in special organs. 



(c) To use a series of different oxidase reagents upon each 

 sample, and to repeat all tests, under parallel conditions, with 

 boiled controls in every case. Our purpose in this was to detect 

 any differences in the behavior of the several reagents when used 

 under controlled conditions upon a large number of materials of 

 plant origin. 



{d) To determine the extent of the distribution of those 

 chromogens in plants which are oxidized to colored compounds 

 by the natural oxidase of the plant itself. These chromogens 

 are the so-called "respiration pigments" of Palladin. 



The Methods of the Investigation 



The method of preparing the enzyme solution varied with 

 the nature of the material. Fleshy parts that were sufificiently 

 large were run through a meat-chopper, smaller ones were grated 

 on a vegetable grater, while leaves, flowers, etc., were macerated 

 in a mortar. Control experiments proved that the iron of 

 the grater had no efifect. In whatever manner the material 

 was finely divided, it was then treated with distilled water 

 and allowed to stand for fifteen minutes. The volume of dis- 

 tilled water varied with the amount and nature of the material, 

 ^fter standing for fifteen minutes with distilled water, the extract 



^'For full details of experimental work and for the arrangement of results ac- 

 cording to the botanical classification see the original dissertation upon which this 

 paper is based. 



