796 ENZYME ACTION 



The fact that Polyporus volvatus may be parasitic seems to have 

 been first suggested by Zeller^ in an unpublished paper. Dr. Zeller 

 writes in part, "The fact that there were still needles on the last 

 year's growth and that the mycelium had spread from the base 

 of the tree up the trunk for 45 to 50 feet indicates that the fungus 

 is parasitic. The writer has no absolute proof of this statement." 



In this region Fomes igniarius is the cause of a serious white heart 

 rot in the common aspen {Populus tremuloides) and also causes a 

 a similar heart rot in mountain birch {Betula fontinalis) . Quite 

 recently Weir^ has reduced Fomes igniarius and Fomes nigricans 

 Fr. to synonomy. 



Thus, the two fungi considered here are not without considerable 

 interest both from the general and economic point of view. 



Methods. 



The cultures of the fungi used in the present study were obtained 

 from young sporophores by the tissue method. As before, the cul- 

 tures were grown on sterile carrots and while still in an active growing 

 condition, removed from the flasks, dried, and ground. All of the 

 enzyme cultures were set up in duplicate and 0.25 gm. of fungous 

 meal was invariably used. Otherwise, the methods followed are 

 those previously described. 



Esterases. 



The esterase activity of Polyporus volvatus and Fomes igniarius 

 was studied by the use of 1 per cent solutions of methyl acetate, 

 ethyl acetate, ethyl butyrate, triacetin, and olive oil emulsion. After 

 twenty-one days incubation, hydrogen ion concentration determi- 

 nations were made of the various filtrates. Positive esterase activity 

 was obtained in the case of both fungi when methyl acetate was used 

 as the substrate. The action on all the other substrates was negative. 



^Zeller, S. M., Wood destroying fungi of Washington. Unpublished paper. 

 ^ Weir, J. R., Some observations on abortive sporophores of wood destroy- 

 ing fungi. Phytopathology, 1915, v, 48-50. 



