1919] 



ROSE— BLISTER CANKER 



127 



For tests in the oxidase apparatus the combined precipitates 

 were dissolved in 20 cc. of water, and 2 cc. of this solution contain- 

 ing the precipitate obtained from o . i gm. of bark was put in each 

 apparatus together with the usual amounts of pyrogallol and water. 



TABLE XVI 



Effect of o. 2 per cent gum arabic, o . 8 per cent gum ar.^bic, and o . 8 per 

 cent gel.atine on oxidation of pyrogallol by healthy and 



DISEASED bark; TEMPERATURE 21-23° C. 



Time of reading 



Healthy 



No 

 addition 



Gelatine 



o . 8 per 



cent 



Gum arabic 



0.2 per 

 cent 



o . 8 per 

 cent 



Diseased 



No 



addition 



Gelatine 



0.8 per 



cent 



Gum arabic 



o . 2 per 

 cent 



0.8 per 

 cent 



At beginning. . . . 

 After shaking 3 



hours 



After 18.5 hours 

 After 42 hours. . 

 Average of 



0.00 



o. 70 

 I 03 



I-50 

 2 



0.00 



0.78 



1-34 

 2. 20 



0.00 



0.65 

 1 .00 



0.00 



o. 71 

 1 .01 

 1-54 



0.00 



1.88 

 2.36 



2.73 

 2 



0.00 



2.23 

 2.69 

 3.18 



0.00 



2.19 

 2.71 



0.00 



2.05 

 2.46 

 2-95 



In table XVIII are given results showing the oxidizing power of 

 these solutions, with and without gelatine (fig. 6). 



The relation observed with bark powder still holds here, that 

 diseased material is more active than healthy. On the other hand, 

 gelatine increases oxidation by the precipitate from extract of 



TABLE XVII 



Reaction of mixtures of bark and pyrogallol vmn gelatine (o . 2 per cent) 



.\XD WITHOUT at VARIOUS STAGES OF OXIDATION PROCESS 



diseased bark, but is without marked effect on that from healthy 

 bark, the reverse of the condition found when bark powder was 

 used. 



There were indications in the preliminary work that the alco- 

 hoHc precipitate from bark extract was easily separated into 2 



