208 
CHARLES O. APPLEMAN 
in this paper show, in a very different kind of plant structure, a similar 
relation between respiration and catalase. 
A very rapid change in respiratory intensity was found to occur 
in sweet corn in the milk stage, after it is pulled from the stalk. Res- 
piration in the corn is very high when it is first pulled but falls off 
rapidly with storage, coming to a constant rate in eight days at 30° C. 
and in ten days at 25° C. At the end of five days' storage at 30° C. 
the respiratory intensity is about half of that found in the corn when 
first pulled. 
The catalase activity in a collateral set of ears was measured im- 
mediately after the corn was pulled and after a period of storage, 
usually five days. The husks were not removed, and as a further 
precaution against loss of water the ears were wrapped in paraffined 
paper and stored in large moist chambers which allowed free access 
of air. The change in catalase activity during storage at 30° C. was 
determined by comparing measurements from the same ear. This 
was made possible by removing three rows of kernels for a catalase 
determination when the corn was first pulled and then removing three 
rows from the opposite side of the ear for a catalase measurement after 
a period of storage. The corn was ground to a pulp in a mortar and 
pressed in a small tincture press. About 0.5 gram of CaCOs was 
mixed with the corn to neutralize the acids liberated during 
grinding. 
Of the milky extract i cc. was added to 25 cc. of distilled 
water. 
After thorough mixing of the diluted extract, 2 cc. were allowed to 
act on I cc. of dioxygen, diluted in the proportion of 25 cc. of dioxygen 
to 75 cc. of water. Bunzell's simplified oxidase apparatus, graduated 
to read positive pressures, was employed for the catalase measure- 
ments as described in the former paper. The manometer readings 
were made at the end of 10 minutes' constant shaking at 30° C. 
Moisture determinations were made at the time of each catalase 
measurement. The percentage of moisture in the corn, under the 
conditions of storage, remained so nearly constant that it was unnec- 
essary to correct for loss of water. 
The catalase measurements recorded in Table I show a decline in 
catalase activity after five days' storage at 30° C. which is almost 
directly proportional to the decline in respiratory intensity in the corn 
after a like period of storage. 
