434 Steward . — On Endospermic Respiration in Certain Seeds. 
io. Table. Comparative Average Output of C0 2 . 
Material. 
Mgms. C 0 2 per gram material per hr. 
Hordeum . 
Zea. 
Ricinus. 
Embryos. (Summer experiments) 
1-2315 
0.4441 
Intact seeds. (Summer experiments) 
0-1689 
0-03346 
Endosperms. (Summer experiments) 
0-006948 ( a ) 1 
0-0818 
Endosperms. (Winter experiments) 
0-01762 
0-01421 ( b ) 
Endosperms. (Winter experiments : material initially 
subjected to diminished pressure) 
0-01438 (c) 
Endosperms. (Winter experiments : re-established ex- 
periment) 
0-02494 
0-01286 ( d ) 
0-01483 (e) 
Material steeped in saturated aqueous chloroform : — 
Endosperms. (Summer experiments) ...... 
0-06521 
Endosperms. (Winter experiments) 
0-02222 
Endosperms. (Winter experiments: material initially 
subjected to diminished pressure) 
Endosperms. (Winter experiments : re-established ex- 
periment) 
0-0I874 
Pure endosperms (A). (Summer experiments) . 
0-02012 
0-004819 (/) 
Pure endosperms (A). (Winter experiments) .... 
0-007564 
0-002661 (g) 
Pure endosperms (A). (Winter experiment: material 
subjected to diminished pressure) 
0-008459 
Pure Endosperms (A). (Summer experiment : re- 
established experiment) 
0-0542I 
Pure Endosperms (A). (Winter experiment : re-estab- 
lished experiment) 
0-006919 
Pure Endosperms (B). (Winter experiment : material 
derived from germinated seeds) 
O.OI934 
ii. The Relative Magnitude of the C0 2 Output by the 
Seed and its Component Parts. 
Separate experiments having been carried out with the intact seeds, 
embryos, endosperms, and pure endosperms of Hordeum and Zea> it is 
possible to make an approximate comparison of the relative respiratory 
activities of the intact seed and its component parts. 
Before entering upon this subject it is desirable to point out the 
difference in constitution which exists between the tissues of the embryo 
and endosperm. The tissues of the former consist of cells with actively 
functioning nuclei and abundant protoplasmic contents ; the great bulk of 
these cells are in a state of vigorous and active growth. The tissues of the 
latter, on the other hand, are composed chiefly of the amyliferous cells with 
senescent nuclei, and a greatly diminished protoplasmic network. It is 
the vitality of these amyliferous cells which has been challenged. Forming 
1 The terms 1 Summer ’ and £ Winter ’ experiments apply only to Hordeum. 
(a) Low temperature experiments. (<?) Material derived from germinated seeds. 
(3) Higher temperature experiments. (/) Material derived from resting seeds. 
(c) Material initially subjected to diminished pressure. 
( d ) Material subjected to prolonged steep. (, g ) Material derived from germinated seeds. 
