43 6 S toward. — On Endospermic Respiration in Certain Seeds. 
statements, however, it is obvious that when the endosperm and pure 
endosperm are considered in conjunction with the embryo, the comparison 
is one which is open to the objection that the attempt is being made to 
compare two things of very different constitution, in that the bulk of the 
weight of the endosperm consists of starch enmeshed in a very small 
quantity of protoplasm, which latter, weight for weight, may be as active as 
that of the embryo. 
Another method of representation may be advanced to express this 
same feature. We may compare the relative C0 2 production furnished 
by an equal number of intact seeds and their component parts, selecting 
for this purpose experimental data which are approximately comparable in 
regard to duration of respiration and range of temperature, and thus con- 
sider the question from this new standpoint. The selected data are arranged 
in the following table : — 
Table. Relative Output of C0 2 . 
Hordeum. 
After hours 
Mgms. C 0 2 
Expt. 
No. of objects. 
°f 
per hotir 
respi 7 'ation. 
per 25 objects. 
( 7 ) 
25 embryos 
4 
0-1216 1 
(10) 
25 endosperms 
4 
0-1259 
(29) 
25 pure endosperms 
3 
0-05286 
( 3 ) 
25 intact seeds 
4 
0-2999 
Zea. 
( 3 ) 
15 embryos 
4 
0.3019 1 
(8) 
15 endosperms 
4 
0.04773 
(25) 
15 pure endosperms 
8 
0-01844 
(2) 
15 intact seeds 
4l 
0-09907 
This mode of representation leads to a change in the order of magnitude 
of the relative output of C0 2 for Hordeum ; this now becomes (i) intact 
seeds, (2) endosperms, (3) embryos, (4) pure endosperms, while the order 
for Zea undergoes no alteration. Reference to the table readily shows 
what a comparatively large share of the respiratory exchanges, during the 
earlier stages of respiration at least, is due to the endosperm and pure 
endosperm in the case of Hordeum when regarded on this new basis — 
a point which can hardly be looked upon as unimportant when economically 
considered. 
Much the same may be said with regard to Zea , where the output is, 
with the exception of the embryo, of a lower order. The large output of 
C0 2 by the isolated embryo of Zea — fully three times greater than that of 
1 Calculated values for 25 objects (Hordeum) and 15 objects (Zea). 
