BEHAVIOR OF PLANTS IN UNVENTILATED CHAMBERS 287 
by the same means 23 seedlings of Pisum sativum L., 26 seedlings 
of Phaseolus vulgaris L. (white kidney bean), 15 seedlings of 
Phaseolus vulgaris L. (black kidney bean), 55 seedlings of Brassica 
alba (L.) Boiss. Duration of the experiments was from 4 to 10 days. 
The seedlings of Pisum and Phaseolus showed a greater height 
in the covered pots than in the uncovered, and, on the average, slightly 
larger leaves in the covered. The Brassica showed no differences 
under the two conditions, height of plants and size of cotyledons 
averaging the same. All species showed falling over about one day 
earlier in the covered pots. In the last days of some of the experi- 
ments some pots of seedlings under cover were ^attacked by damping 
off; the "falling over" mentioned is due to exhaustion of the plants, 
not to damping off. 
Three species of larger leafy plants were subjected to the same test 
as the foregoing seedlings. The air in the darkroom being constantly 
brought in from the greenhouse in which the potted plants had been 
growing, there was no danger of the transposed plants suffering from 
a too dry atmosphere. The Ricinus plants used and the Bryophyllum 
were from 50 to 65 cm. tall, and cylinders correspondingly high were 
used to cover them. The experiments were made in July and August. 
There were used 3 plants of Ricinus communis L. under zinc 
cylinders, and 6 plants uncovered. No differences in their growth or 
other behavior could be detected during the 10 days of trial. All 
began dropping their leaves after 7 days, and in 10 days from the 
beginning of the experiment all leaves had fallen. 
Twelve plants of Bryophyllum calycinum Salisb. were put under 
experiment, 6 for 16 days and 6 for 27 days; in each experiment, 3 
plants were kept under zinc cylinders and 3 were left uncovered and 
thus exposed to the moving air. -No differences in behavior could 
be seen. The new leaves unfolded in the dark were pale yellow, but 
no leaves fell from either the covered or uncovered plants. 
Growth of Plants in Ventilated and Unventilated Chambers of Equal Size 
Series III. — The chambers used in this series were two wooden 
culture boxes, 20x20x50 cm. Each box had a closely fitting 
rabbeted door. In each box were placed three 4-inch pots of seedlings 
of Brassica alba (L.) Boiss. about 4 cm. tall, growing from earth. 
These boxes were placed in an interior darkroom with a capacity of 
