1910] APPLEMAN—CATALASE 185 
If the potato is ground with calcium carbonate to neutralize the 
acids freed by the grinding, and 5 cc. of the extract is at once diluted 
with 50 cc. and kept at a temperature of 20° C. or below, this rapid 
degeneration may be overcome and comparable results obtained 
<*>) ta 
Fic. 1.—Apparatus used for catalase determinations: 1, thin-walled bottle; 2, 
separatory funnel; 3, gas burettes; 4, thermometers; 5, weights; 6, water bath; 7, 
water meniscus; 8, water level in bath; a, stopcock for running the hydrogen peroxid 
into bottle; b, stopcock for controlling the flow of oxygen into the burette; c, stop- 
cock for equalizing the air pressure in burettes. 
without any difficulty. It is necessary, however, to maintain the 
same period of time for grinding, as there is a slight degeneration 
even under the above conditions, due to another cause, as we shall 
see later. The shaking must also be constant and uniform during 
the determination. 
Table II shows the effect of grinding and storage with calcium 
carbonate. After grinding two potatoes of equal weight, one with 
