468 
Kidd and West . — The Controlling 
Table XI. 
Exper. 3. Passage of Carbon Dioxide into the Seed. 
Eight inhibited seeds showing secondary dormancy compared with 
eight normal seeds fully swollen after one day on wet sand. Both outer and 
inner testas were left intact. 
Mercury rise in millimetres. 
Time. Inhibited seeds. Non-inhibited seeds. 
5 min. 12 
10 „ 27 
35 » 43 
150 „ 7 1 
12 
27 
43 
7i 
Exper. 4. Passage of Carbon Dioxide into the Seed . 
Twenty inhibited seeds immediately after removal from 30 per cent, 
carbon dioxide compared with twenty normal seeds fully swollen after one 
day on wet sand. In this experiment the non-inhibited seeds allowed 
a quicker uptake of carbon dioxide than the inhibited ones, which was to 
be expected from the known difference between the initial internal con- 
centrations of carbon dioxide within the seeds, i.e. a difference of 30 per 
cent, approximately. 
Table XII. 
Exper. 5. Passage of Carbon Dioxide out of the Seed. 
Same seeds as in the above experiment, the carbon dioxide being 
displaced by a current of nitrogen after four hours. Weight of twenty 
seeds = 0-24 gramme. Approximate volume = 0*25 c.c. 
Escape of carbon dioxide. 
Time. Inhibited seeds. Non-inhibited seeds. 
85 min. 0*125 c.c. 0*135 c.c. 
16 hours 0175 c.c. 0*1950.0. 
Exper. 6 and 7. Passage of Carbon Dioxide into and out of the Seed. 
The same seeds as in the above experiment, carbon dioxide being again 
run into the apparatus. The subsequent rise in four and a half hours amounted 
to 0*140 c.c. in the case of the inhibited, and 0*160 c.c. in the case of the non- 
inhibited seeds. The carbon dioxide was then again displaced by nitrogen, 
and the subsequent escape of C0 2 from the seeds proceeded at an equal rate. 
Seines B. 
In these experiments, free testas of equal size were obtained by cutting 
off a sector of the seed and carefully removing the embryo. The per- 
meability to oxygen of testas from inhibited and non-inhibited seeds 
respectively was compared by direct experiment. 
Text-fig. 3, a , represents the apparatus employed. The testas, P, to be 
compared were fitted over two narrow glass tubes, A and B, of equal bore, 
