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BOTANICAL GAZETTE [february 



A test for catalase was run also on the fungus powder pre- 

 viously mentioned, using 0.03 gm. in each tube and calculating 

 the results to the basis of o.iogm. The average mercury rise 

 (positive pressure) produced in 3 tubes was i .65 cm. in 5 minutes 

 and 2.57 cm. in 10 minutes, or, calculated to the basis of o . 10 gm., 

 5.49 cm. in 5 minutes, and 8.55 cm. in 10 minutes. It is worthy 

 of note that a powder prepared from Nummularia mycelium grown 

 in Raulin's solution, which is acid to litmus, showed no catalase 

 activity. Experiments with different amounts of material showed 

 that the positive pressure varies directly with the amount of 

 material used. It was deemed legitimate, therefore, to calculate 

 all results to the basis of o . 10 gm. of bark powder, and the figures 

 for final tabulation were so calculated. 



The results for samples 14, 16, 18, all from the same tree, show 

 that diseased bark (sample 18) had more than twice the catalase 

 activity of seemingly healthy bark 5 cm. away from the canker 

 (sample 16), but only nine-tenths of that of bark from a sound 

 unaffected limb on the same tree (sample 14). Dead cankered 

 bark from this tree (sample 20) had 4 times the catalase activity 

 of healthy bark, 12 times that of seemingly healthy bark next the 

 canker, and nearly 5 times that of diseased bark. In the case of 

 samples 9 (healthy) and 10 (diseased), the results are reversed, 

 since the diseased had a catalase activity nearly 7 times greater 

 than that of the healthy bark. The reason for the discrepancy 

 between these two sets is not clear. The high catalase activity 

 of sample no. 10 can hardly have been due to the presence of 

 Kchens, etc., or of an admixture of really dead bark, for precautions 

 were taken when the samples were removed to avoid these sources 

 of error. From the present data the only conclusion that can be 

 drawn is that diseased bark from different trees varies considerably 

 in its catalase activity, and that in general the more completely 

 the bark is destroyed by the fungus the greater is its catalase 

 activity. This condition is probably to be explained by the 

 presence in the diseased bark of considerable amounts of mycelium 

 which, as shown, produces a catalase of its own. 



The seemingly healthy bark near the canker when compared 

 with sound and with diseased bark appears to form an exception 



