108 BOTANICAL GAZETTE : [AUcUst 
possess this ability to produce roots along portions of the stem that 
are kept wet. Sometimes, as in Veronica anagallis, the root primor- 
dia are already laid down, but in most plants these are not present. 
Kies believes that in these cases the development of the roots is due 
to the increased absorption of water, and holds this factor to be of 
great importance in other regeneration phenomena. The following 
experiments will throw light upon this. 
The question was attacked by two opposite methods: the effect 
was determined of (1) growing plants without injury or any removal — 
under such conditions as would increase the water in the plant to the _ 
highest amount possible; (2) of supplying the other conditions for 
regeneration and at the same time decreasing the water content of the — 
plant to the least possible amount compatible with actual existence 
Experiment 9.—Six plants in pots were placed under bell jats 
whose inner surfaces were lined with wet filter paper. The plants 
grew rapidly, but no regeneration occurred. 
Experiment 10.—The same experiment was repeated with five 
other plants, with the same result. While this usual method of 
forming a moist chamber gives an atmosphere that minimizes trans 
piration, it does not altogether inhibit it. This objection was over 
come in two ways (experiments 11 and 17). : 
Experiment 11.—Two plants were set in a large bell jar, and this 
was set over a vessel of water so that the bottom of the bell jar was 
just below the surface of the water. This water was heated to am 
kept at a constant temperature of 33°. The air of the greenhoust a 
averaged 18-20°, while that in the bell jar was 24°, a good growing 
temperature for this plant. The air surrounding the plant was thus 
saturated from a water surface whose temperature was + a higher that 
the temperature of the plant, which entirely inhibits any evapor™ 
from the latter. The plants grew rapidly, but the primordia at the 
base showed no signs of developing. Here the plant is undoublet™ — 
saturated with water. | 
Experiment 12.—Attempts were made to prevent transpiration 
covering the leaves with vaseline, cocoa butter, or soft wax, but in? 
case was the development of the buds produced. = 
Experiment 13.—In the moist chambers described the whole pe 
was in the moist air. Two plants were next arranged, each in a ag 
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