

















356 Dr. E. Drabble and Miss H. Lake. | May 12, 
Table LV. 
| Per cent No. Curvature . . 
CO,. of peas. | after 30 mins. 1 hy. 1 br. 45 mins. 2 hrs. 15 mins. 
Oe cca eit: 8 3b— 5b— 3b, 8b— b+, 26, 36— 
A cd 8 0 6, 8b— b+, 26, 56— 36+, 2b, 3b— 
Hie ore sds 8 b, b— 26, 4b— 264+, 3b, 36— b+ 4+, 264+, 46 
| | 
Table V. 
Per cent No. Curvature after ‘ : 
CO.. of peas. The eating. 1 hr. 45 mins. | 2 hrs. 30 mins. 3 hrs. 
AN eee aster 12 2b, 6b — 8b+, 2b, 2b— | 64+ +,8b4+,3b | 8b++4+, 86+, b 
PAs acne 12 8b— 654+, 2b, 4b— 96+, 2b, b— Be +,106+, 6— 
Table VI. 
Per cent No. Curvature : ; : t : 
COs. of peas. | after 30 mins. 1 hr. 1 hr. 30 mins. 2 hrs. 2 hrs. 30 mins. 
OF 2 Geers, 12 0 Ab — 3b, 6b— 6+, 5b, 56— 56+, 6b 
Oc bneea. 12 0 63— 5b, 4b— 364+, 56, 8b—|64+ +,664+,3b,b— 
i 0 re 12 0 b,7b— |2b4+,6b,3b—| 8b+,3b-— |b6+ 4,964, 6, b- 
In considering the mode of action of carbon dioxide several possibilities 
present themselves. It is conceivable that increase of the partial pressure 
of carbon dioxide above a certain point, by the mere presence of an increased 
number of molecules of this substance, may interfere with the liberation of 
more carbon dioxide in the ordinary respiratory function, so depressing the 
activity of the cell. On the other hand, or in addition to this mode, the 
carbon dioxide may exert a direct action on the protoplasm itself. Although 
this seems to have been the generally accepted explanation, it appears to 
afford but a very imperfect picture of the true course of events. Recent 
work on the action of poisons suggests with considerable force that in many 
cases dissociation of the molecule precedes the manifestation of physiological 
effect. Walker (12) has shown that when carbon dioxide is dissolved in 
water, a solution containing unchanged COs, H2CO3 and dissociated H2CO3 
(H* and HCOs7) is produced, the proportion of the dissociated substance 
depending on the strength of solution. 
