248 BOTANICAL GAZETTE [APRIL 
brought in through tube X. In such a contrivance the oxygen 
pressure in the water, which was reduced through respiration, 
would be continually renewed on the side facing the air chamber. 
Table IV shows no aerotropic curves with the 54 seedlings of 
Cucurbita Pepo, 40 of which were neutral, while the remaining 14 
were divided equally between positive and negative. The angles 
of curvature were not large and the growth was slight at first, 
due to insufficient pressure of oxygen. However, as more and 
more oxygen diffused from the chamber the roots grew more 
rapidly. 
TABLE IV. 
(Plus sign indicates curve toward air chamber.) 
a be = ee 
S| & £ e && | Gas above 
: = = 52 Ba water 
Species se < 2 § =e — | o | Angle Growth 
as | 28 
i : & 6 | 3 = |sco,| ¢air 
ia) 
ucurbita Pepo.| 16 | 10 27° 3-9 Io go 214 | 10] 5-45° Little first 6 hrs. 
Cucurbita Pepo.| 18 | 10 28 3-9 30 jo | 3 | 2 | 13 | 5-45° | Little first 6 hrs. 
Cucurbita Pepo.| 20 | 22 27 1-3 60 40 | 2 | 2 | 17 | 5-20" Little first 4 hrs. 
Dota cia 54 7 | 7 | 40 
When the water above the gas chambers was replaced by mix- 
tures of hydrogen and air in varying percentages, approxi- 
mately the same results were obtained both in curvature and 
growth, as shown in Table V. 
TABLE V. 
(Plus sign indicates curve toward air chamber.) 
al : 
| 3 z = & | Gas above 
= ° h ie 
: 3] a3 A c water 
Species we a Seo : —|o]| Angle Growth 
yar! } E. 2 & 8 
o-=| & S 2s : 
3 2 fe es &H | #air 
Zea tee 
popcorn) .,| 18 7 25 3-9 to .. | 2] 16] 5-30° | Good growth 
Cucurbita Pepo 12 30 2-4 25 7 2] rj 4g — |Considerably retard’d 
Cucurbita Pepo | 18 2-4 3314| 66% 14| 5-20° | Slight during first 6 
or 7 hrs. 
Zea Mays 
popcorn) ..| 19 | ar 25 3-5 50 | 50 2| 14 | 10-60° | Not apparently 
Zea Mays ? retarded 
(popcorn) ..| 16 | 22 iS ti qe | as.ch a} oe 10 | sae. Slight during first 5 
hrs. 
Doteligg? Se 9 | tr | 69 
