184 BOTANICAL GAZETTE [SEPTEMBER 
conception, and if no zymase is present the lactic acid is oxidized 
to oxalic acid by oxidizing enzymes. If zymase is present, it 
splits the salts of lactic acid up into alcohol and carbon dioxid, 
the work of the lactacidase according to BUCHNER and MEISEN- 
HEIMER. This work of Kout’s, if confirmed, brings to catalase 
a very important réle in physiological processes as an oxidizing 
enzyme. 
METHODS ; 
The following method was employed in all the catalase deter- 
_ Minations except where otherwise stated. The apparatus used is 
shown in fig. 1. The potato was grated rapidly on a nutmeg grater 
with frequent dipping of the grated surface into calcium carbonate. 
After grating, the pulp was ground for two minutes in a mortar 
with quartz sand. The extract was then pressed lightly through 
two layers of absorbent cotton and one of cheese cloth. After 
mixing, 1 cc. was withdrawn immediately and placed into the 
bottle used for the determination, and 1 cc. of cold water added. 
The apparatus was then placed into a water bath at 20° C. After 
the apparatus had attained the temperature of the bath, 5 Cc of 
Oakland 3 per cent hydrogen peroxid (dioxygen) were run into the 
bottle from the separating funnel 2. The stopcock a was 
opened 15 seconds before the minute. On the minute, shaking 
was begun and continued with as much regularity as possible to 
the end of the experiment. On the quarter-minute the stopcock 
6 was opened and the. oxygen allowed ‘to run into the gas burette. 
On the half-minute the stopcock 5 was closed and a reading made 
at the burette. Stopcock ¢ was now opened until the memiscl — 
in the burettes were again level. At the three-quarter mark ™ a 
stopcock 6 was opened again and closed on the minute for a reading: 
This procedure was continued with readings every 30 seconds for 
three minutes. With longer periods the experimental error becomes 
greater on account of lack of uniform shaking. 
EFFECT OF GRINDING WITH CALCIUM CARBONATE 4 
GrUss (10) reports that it is impossible to make quantitative 
determinations of catalase in the fresh potato extract on accoun 
of the rapid degeneration during the grinding and subseque? 
