43 8 S toward, On Endospermic Respiration in Certain Seeds , 
displacement of the gaseous respiration products by atmospheric air at 
any subsequent stage. These have been termed 4 non re-established * 
experiments. 
They present a common feature as regards the output of C0 2 , which 
is more or less independent of the temperature changes experienced during 
each experiment In general they are characterized by an apparently high 
initial output of C0 2 , which is succeeded by a further slight rise ; and this 
is subsequently followed by a progressive diminution of the output as the 
experiment progresses. This apparently high initial output, followed by 
a slight rise, may perhaps be -explained on the ground that, during the 
initial stage of the experiment in certain cases, the C0 2 had not acquired 
its maximum tension within the tissues, thus leading to a delay in the 
outward diffusion of this gas. When this tension is reached, diffusion 
proceeds more regularly, and then the C0 2 attains, in the gaseous space 
without, what may be termed its normal concentration. 
The progressive diminution in the output apparently turns on the 
changing concentrations of 0 2 and C0 2 in the gaseous medium surrounding 
the material ; the former slowly diminishing, the latter slowly increasing ; 
the combined effect of which is probably to produce the results observed, 
i. e. an increasing diminution in the output of CO* 2 as the experiment 
progresses. Further, the C0 2 , when its concentration is sufficiently great, 
probably exercises a retarding or poisonous action on the respiratory 
activity of the tissues of the endosperm, or of the respiratory enzymes which 
they may contain. 
13. Re-established Experiments. 
Certain experiments with the endosperms and pure endosperms of 
Hordeum were interrupted during their course ; the gaseous respiration 
products, after withdrawal of the sample for analysis, being displaced by 
atmospheric air which was made to pass through a sterilized cotton wool 
filter; the experiment thus undergoing re-establishment at certain definite 
intervals. 
The results of these re-established experiments show that, in contrast 
with those furnished by the non re-established experiments, the output of 
C0 2 does not exhibit that progressive diminution which was a common 
feature of the latter experiments ; instead, the output under these circum- 
stances is maintained slightly above or below a certain mean level. This 
fact tends to show that in these instances of endospermic respiration the 
process cannot be regarded as a mere physical process of diffusion of 
C0 2 from a storage source of this gas (the endosperm), accompanied by 
a simultaneous absorption of 0 2 ; but that there is a more or less regular 
production of C0 2 , accompanied by 0 2 absorption, which is well maintained 
over intervals of time covering several hours. 
