

1905. ] Effect of Carbon Dioxide on Roots. 355 
those in 0°5 per cent. and in 0:2 per cent. following in decreasing order 
(see Table VI). 
A few words of explanation may be added to the preceding account of our 
results. Attention was principally focussed upon the first appearance and 
relative magnitude of the earlier curvatures. In addition it should be noted 
that in COz free air, in air itself, in 0°2, 0°5, 1, 2, and 3 per cent. COs, all the 
roots finally exhibited very large curvatures, while in 74 per cent., and in 
10 per cent., the actual power of response seemed to be not only delayed, but 
actually diminished to a very large degree. 
Throughout the experiments the range of temperature did not exceed about 
one degree Centigrade, namely, from 15° to 16°, and in every case any such 
small range was exactly similar for each set of peas used in comparison. 
A few representative tables have been selected, and are given below :— 











Table I. 
Per cent.| No. Curvature hie: : : r P 
COy. of peas. |after 45 mins.| 15 mins. 1 hr. 45 mins. | 2 hrs. 15 mins. | 2 hrs. 45 mins. 
WAGE 8s oan 6 0 3b — b+, 6, 2b— b+,6,3b— |264+ 4+,2b4+,6 
1 rn 6 3b— 26, 3b— 264+,6, 8b— | 264+, 26, 3b— | 64+ +, 264, 26 
iO) Saar 6 O 0 26— 3b— 3b, 2b— 
Table II. 
Per cent. No. Curvature 1 hr. | 1 hr. 30 mins. 2 hrs. 3 brs. 
CO,. | of peas. | after 30 mins. 

| | a —_————_ 

Biipe ccs 8 4 10) 2b— 3b— 2b+, 6, 46— |b4+ 4,404, 26, b— 









32 ee 8 O 3b— 3b—, b 6+, 26, 3b— | 364+ 4, b+, 2b, b— 
ee. 8 0 2b — 2b — 6, b= 36, 2b— 
Table ILI. 
Per cent. No. Curvature : 
CO,. of peas. | after 30 mins. 1 hr. 1 hr. 30 mins. 2 hrs. 3 hrs. 
0h eee 6 b— 2b 36,b— 26+, 6, 2b— 46+, 6, b— 
ee ee 5 2b— 2b, 2b— | 26+,26,6— | 364++4,6+,6 4b++,6+4 
Scere oes 6 b— b, 86— | b+, 8b, 2b— |64+4,4b4+,b—| 264 4,404 
