1921] SHERMAN—DORMANT SEEDS 3 
ripening or aging. Furthermore, since many workers claim that 
catalase activity varies with the respiration, catalase determina- 
tions have been made on most of the seeds used. 
Methods 
Catalase activity was measured by the volume of oxygen set 
free from hydrogen peroxide (the Oakland Chemical Company’s 
dioxogen) by a given weight of seeds. The apparatus was essen- 
tially that described by APPLEMAN (1), and the routine procedure 
was to grind the seeds for one minute in a mortar with sand and 
calcium: carbonate, add 5 cc. of distilled water, and grind a second 
minute. The contents of the mortar were then transferred to a 
bottle which was placed in a water bath at 25°C. The level of the 
gas burette was adjusted, and after sufficient time had elapsed for 
the seed suspension to come to the temperature of the bath, the 
exit of the gas burette was closed. Constancy of level of the water 
meniscus in the gas burette was assumed to indicate stability of 
temperature. Thereupon the cock of the dropping funnel was 
opened on the minute, and 5 cc. of dioxogen was allowed to flow 
into the bottle, which was immediately set shaking. Readings of 
the volume of oxygen liberated were taken on the gas burette every 
minute for the first five minutes and on the tenth minute also. 
The respiration determinations were made by means of a respi- 
rometer designed by CRocKER (26). This consists of a cylin- 
drical glass chamber fitted with a glass stopper through which 
pass two tubes, one a manometer and the other a short, straight 
tube provided with a stopcock by which the chamber can 
be closed to the surrounding air. Seeds which had been soaked 
for twenty-four hours and thereafter stored on moist filter paper 
at about 10° C. were placed in a porcelain hooded holder, designed: 
by Harrincton (25). This holder was supported within the 
respirometer on projections from its wall about 1 cm. above the 
se. The respirometer was placed in a water bath at constant 
temperature, and after half an hour the mercury in the manometer 
was brought to a level and the stopcock closed. When the experi- 
ment was to be brought to an end, the difference between the 
mercury levels in the two arms of the manometer was measured, 
and a known volume of caustic potash was introduced into the 
