S toward.— On Endospermic Respiration in Certain Seeds. 433 
9. Influence of Temperature on Respiratory Activity. 
In comparing the respiratory activity of the seed and its separate 
components (embryo, endosperm, and pure endosperm), the output of C0 2 
in milligrams per gram of moist material has been adopted as a working 
criterion. 
The discussion of the influence of temperature on the respiratory 
activity of the endosperms and pure endosperms of Hordeum presents 
considerable difficulty, because the experiments were performed under 
variable temperature conditions, and during the summer and winter 
months. 1 
The general statement may be made that, both in the * summer ’ and 
‘winter’ experiments with endosperms and pure endosperms of Hordeum 
the higher range of temperature is responsible for an accompanying in- 
creased output of C0 2 . The influence of temperature on the respiratory 
activity, though variable, is quite manifest. The comparatively low output 
of C0 2 in the winter experiments with similar objects, while attributable 
in part to the lower range of temperature under which these experiments 
were performed, is also probably associated with the ageing of the seeds 
during the interval of time which elapsed between the performance of the 
two series of experiments. 
The majority of the experiments with Zea were executed under more 
constant temperature conditions, and here quite safe comparisons regarding 
the influence of this factor may be made. Thus, if experiments 5 and 6 
(endosperms) are compared with almost any of those which follow (endo- 
sperm experiments) for a time interval extending over four to eight hours, 
it is seen that for a rise in temperature of approximately 5 0 C. the output 
of C0 2 undergoes an increase of from 2-2J times as great. 
Of the experiments with the endosperm of Ricinus , one was with 
water-steeped material at a comparatively high temperature, the other 
with chloroform-steeped material at a lower temperature. The output in 
the latter experiment is significantly lower than in the former ; in how far 
the lower temperature has influenced the result it is impossible to decide 
from the data collected. It is noteworthy that during the first respiratory 
CO 
interval the relation 2 does not vary greatly in the two experiments. 
Wo 
1 The experiments with Hordeum and Ricinus were made in the University Experiment House 
of the Edgbaston Botanical Gardens ; those described with Zea , by the kind permission of Professor 
Adrian Brown, were undertaken in the Laboratory of the Department of Brewing of the University 
pf Birmingham. 
