30 
BEHAVIOR TOWARD ALKALINE SILVER SOLUTION. 
A very subtile reagent for aldehyde groups is prepared by adding 
a few drops of dilute caustic soda to an ammoniacal silver solution 
which contains only a small excess of ammonia. Such a solution, con-. 
taining 2 per cent silver oxid, was added to 20 ce. of the a-catalase 
solution above mentioned. After standing twenty-four hours a very 
small amount of dark sediment was formed, but the solution still had 
its original degree of catalytic power. A considerable separation of 
metallic silver and a destruction of the catalytic power would naturally 
have been expected were ordinary aldehyde groups concerned in the 
activity. : 
In a second test freshly precipitated silver oxid was suspended in 40 
ec, of a solution of crude f-catalase (obtained by salting out tobacco 
extract with sodium sulphate) and the mixture tested after standing at 
the ordinary temperature for two days. To this and the control solu- 
tion were added several drops of ether. In testing both solutions at 
the same time, it was found that while 20 ce. of the control solution, 
after the addition of 10 cc. hydrogen peroxid, developed 53 cc. of 
oxygen in two minutes, the filtrate from the silver oxid took three 
minutes to do the same; hence the injury caused by silver oxid was 
only moderate. 
GENERAL OCCURRENCE OF a-AND £-CATALASE. 
Numerous tests have established beyond a doubt that catalase is of 
general occurrence in the vegetable kingdom. No living plant or 
vegetable organ tested was found free from it, some of the plants 
containing more of the soluble and others more of the insoluble form. 
Leaves from various plant families showed principally the insoluble 
catalase, in some cases only slight traces of the soluble kind being 
noticeable, while in various seeds the soluble kind was found present 
in larger proportions. 
Healthy green tobacco leaves, taken from the greenhouse on Decem- 
ber 22, were dried at 40° C. After being ground to a fine powder 2 
grams were extracted with 40 grams of water for three hours at the 
ordinary temperature. The filtrate gave reactions for oxidase and 
peroxidase, but showed no catalytic power on hydrogen peroxid, and 
therefore contained no #-catalase.t The well-washed residue, sus- 
pended in 20 ec. water, developed, after the addition of 12 cc. hydro- 
1Traces of 6-catalase may be observed, however, when the green tobacco leaves 
have not been dried, but are ground and expressed in the fresh state, the clear fil- 
trate being directly tested. It must be borne in mind, however, that the frequent 
presence of nitrates in the leaves may decrease the action on hydrogen peroxid to a 
considerable extent, which might lead sometimes to the inference of the presence of 
only very small quantities of 6-catalase. 
