MOSAIC DISEASE OF TOBACCO. 103 



diastase in the old conception of the term. Rather it might be said 

 the action is on the primary enzyme concerned in diasta ic activity, if the 

 newer concept of diastatic activity above advanced is true, as it would 

 seem to be from the unpublished investigations of Roessler of the Uni- 

 versity of Prague, who was able to separate by salting out from a very 

 carefully prepared solution of the ordinary diastase at least two compo- 

 nents having the respective actions above mentioned. In no case, as 

 indicated by the color reaction obtained, did we get a complete hydrol- 

 ysis of a large amount of starch, the process only being carried on, ap- 

 parently, as has been indicated, — as far as the erythro-dextrine and 

 achro-dextrine stage. It was attempted in our experiments to isolate 

 or rather separate out diastase in a more or less pure form from the leaves 

 of healthy and diseased plants, and although certain results were obtained, 

 it was rather a difficult matter, as in the writer's experience it has been 

 found that diastase is one of the most difficult of the enzymes to purify 

 to any extent. The protective colloids, etc., during the purification are 

 separated away from the enzyme aggregate, and the purer ferment be- 

 comes less active. The reason for this cannot be very well explained at 

 the present, but it is the experience of all investigators with diastase that 

 this is a fact. However, results were obtained which seemed to indicate 

 that the diseased leaves contain relatively less "diastase" than do the 

 normal healthy leaves. 



Chlorophyllase. — This enzyme has been found to be always present 

 with chlorophyll in amounts directly proportional to the amount of 

 chlorophjdl present, and according to Willstatter and Stoll^ does not 

 bring about an hydrolysis but an "alcoholysis," 



RCOOCsoHsa — C2H5OH . RCOOC2HS — C20H39OH 



in the presence of ethyl alcohol. It forms the alcohol phytol, CooHsgOH, 

 from the radical in the presence of ethyl alcohol and not water only. 



Ver}^ httle is known about its action in the plant cell, and although the 

 writer was able to demonstrate its presence in both healthy and diseased 

 leaves, no quantitative data were secured as to its relative activity in 

 healthy and diseased tissue. Until better methods are worked out for 

 its purification and rapid determination it would be futile to hazard an 

 opinion in regard to its specific action in the ceUs of healthy and diseased 

 leaves. 



Oxidases and Peroxidases. — Woods (loc. cit.) was one of the first to 

 observe that in mosaic-diseased leaves the oxidase activity was greatly 

 increased. Since then it has been found that in the curly dwarf disease 

 of the potato and sugar beet the oxidase activity is greatly increased in 

 the diseased leaves as compared with that of the normal. These two 

 diseases have been for the most part regarded as physiological, and it is 



1 Willstatter and Stoll: Unt. uber Chlorophyll XI und XIII. tjber Chlorophyllasa. Liebig's 

 Ann. der Chemie., 378. 18 (1910); 380, 148 (1911). 



