410 BOTANICAL GAZETTE [NOVEMBER 
only obtained, however, under certain conditions which are con- 
cerned with the stage of development of the fruit. 
After some preliminary experimentation, 3 fruits of the same 
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Fic. 1.—Curves representing de- 
composition of hydrogen peroxide: upper 
B represents action of an extract 
of a well ripened pineapple; lower curve 
a neeerets action of ~ gewe of a 
sent presen of oxygen produced (x 
pressed in of liquid paraffin in a 
paraffin manomete) abscissae represent 
time in minutes. 
MINUTES 
variety were selected. One 
was quite ripe and soft; 
another, although it had 
turned yellow, was still rather 
hard; the third had only 
partly lost its green color. 
The juice of each of these 
fruits was pressed out sepa- 
rately in a mortar, filtered, 
and the catalase activity de- 
termined by mixing 2 cc. of 
the juice in each case with | 
too cc. of 0.05 M hydrogen 
peroxide and measuring the 
pressure of the oxygen 
evolved. For this purpose 
the hydrogen peroxide was 
placed in a 300cc. bottle 
which was provided with a 
3-hole stopper carrying a 
small separatory funnel in 
which the juice was placed, 
a paraffin manometer and a 
tube, closed by a stopcock, for 
the equalization of the initial 
pressure. The whole appara- 
tus was submerged in a ta: 
of water with a glass wall, the 
temperature of which was 
kept constant. After all the 
solutions had reached the same temperature the stopcock of the 
funnel was open and the juice allowed to run into the peroxide. 
On closing the stopcock of the funnel, as well as that of the pres- 
sure tube which had previously been open, the reaction was started 
