234 SOME RECENT RESEARCHES IN PLANT PHYSIOLOGY 



whole plant may be under their influence. Bourquelot 

 and Bertrand (1895, 1896), Zellner (1907), Pringsheim 

 (1909), Kastle (1906), and others, have shown that pheno- 

 lases are of almost universal occurrence in fungi, whereas 

 the distribution of tyrosinases is not so general. Clark 

 (1910) tested a large number of groups of phanerogams 

 and pteridophytes, and has found phenolases to be of 

 very general occurrence, the peroxidase without peroxide 

 being most frequently encountered. The absence of 

 oxidase in certain acid saps was noted. Moore and Whitley 

 (1909) had previously drawn attention to the fact that the 

 pulp of lemons, limes, and oranges, was free from oxidase, 

 though it occurs in the seeds. It has recently been shown 

 by Reed (1914) that peroxidase can be located in the tissue 

 between the compartments of the fruit of the orange by 

 means of microchemical reagents. 



Passerini (1899), too, studied the distribution of oxidase, 

 but restricted his investigation to determining the presence 

 of organic peroxide. The complete system was found in 

 eighty-one species from forty-nine families. This wide- 

 spread occurrence of oxidases is demanded by Palladin's 

 theory of the respiration of plants, and there seems no 

 reason to doubt that they occur, in various degrees of 

 activity, in every living cell. Owing to the possibility of 

 treatment with reagents liberating inhibitors from vacuoles 

 or specialized regions of the protoplasm, negative results 

 must always be regarded as an incentive to further research 

 in the direction of effecting a separation of inhibitor and 

 oxidase. 



In this connection the behaviour of the marine algse 

 alluded to in a former section urgently calls for further 

 investigation. It was found by the writer (1914, 2) that, 

 out of twenty-nine members of the Chlorophyceae, Phseo- 

 phycese, and Rhodophyceae examined, only Furcellaria 



