iqiq] 



ROSE— BLISTER CANKER 



133 



Pleurococcus, etc., since microchemical work had shown that such 

 growths have a high catalase activity. The bark was then shaved 

 off, ground in a meat chopper, and allowed to dry on filter paper 

 at room temperature. In the case of samples 9, 10, 14, 16, 18, and 

 20, calcium carbonate was added during the grinding process at 

 the rate of 0.5 gm. to each 10 gm. of unground bark, to prevent 

 destruction of catalase by the acids of the bark (2) or of the hydro- 

 gen peroxide used. The dried bark was finally ground to a powder 

 and only that part used which passed through an 80-mesh sieve. 



TABLE XX 



Catalase activity of apple bark 



Sample 



NUMBER 



3 



4 

 9 



10 

 13 



14 



15 

 16 



17 

 18 



19 



20 



Description of sample 



Healthy, from sound limb, no car- 

 bonate 



Diseased, no carbonate 



Healthy, from sound limb, plus car- 

 bonate 



Diseased, plus carbonate 



Healthy, from sound limb, no car- 

 bonate 



Healthy, from sound limb, plus car- 

 bonate 



Healthy (?) 5 cm. from canker, no 

 carbonate 



Healthy ( ?) 5 cm. from canker, plus 

 carbonate 



Diseased, no carbonate 



Diseased, plus carbonate 



Dead, no carbonate 



Dead, plus carbonate 



Tempera- 



TLTIE 



23-5 



21 .0 



21 .0 



22.0 



20.5 

 22.5 



Positive pressure in cm. 



After s min. 



o. 10 



0-55 



0.83 

 5-49 



0.52 



1.83 



0.54 



0.73 

 0-55 

 1-47 

 5.00 

 7.01 



After 10 min. 



O.IO 

 0-9S 



I . 26 

 8.59 



o. 70 



3.02 

 0.65 

 1. 01 



0.81 

 2.74 



7-37 

 12.17 



Tests were made at room temperature by means of the simpli- 

 fied Bunzell apparatus, using 0.03 or o.iogm. of bark powder, 

 I cc. of water, and 4 cc. of 25 per cent hydrogen peroxide. After 

 the experiment was set up the apparatus was allowed to stand for 

 half an hour, when the manometers were closed and the solutions 

 mixed. The apparatus was shaken for 10 seconds at the end of 

 each minute and readings taken after 5 and 10 minutes. All tests 

 were made in duplicate or quadruplicate, a water blank being 

 included for temperature corrections as in the oxidase work. 



