New comb e, Sensitive Life of Asparagus plumosus. 
17 
its negative geotropism up to the cessation of growth. Plants, 
revolving as here indicated, have in 9 tests when the revolution 
was stopped before the plants were mature, shown negative geotropic 
cnrves in both the main axis and in the lateral branches. 
II. Relation toward Light. 
The main axis of the seedling shoot and of the shoots arising 
from the rhizome are stronglv positively heliotropic from their 
first appearance above ground. to the cessation of growth with the 
tip in the horizontal position. The lateral branches of lower Order 
than the needles are certainly less responsive to light than is the 
tip of the main axis, for they are but slowly and slightly deflected 
from their straight course by one-sided illuraination. The lateral 
branches are under the domination of the 2 Stimuli which cause 
them to take the horizontal position and their “proper angle" in 
this horizontal plane, and they are not easily diverted from their 
reaction to these two factors. The tip of the main axis, on the 
other hand, will readily bend aside from its straight course in re¬ 
sponse to light, even when the diageotropic shoot has unfolded 
the most of its branches and needles. 
One of the efiects of growing these Asparagus plants in the 
dark is to extend elongation enormously. A shoot that would grow 
to a total length of 15 or 20 cm in the light will attain an in¬ 
definite length in the dark. I have raised several such shoots to 
a hight of over 200 cm, and discontinued the experiment with no 
indication of growth ceasing. This striking result in etiolation is 
accounted for to a limited extent by the greater length of internodes 
in the dark. The internode length of the main axis of a plant 
growing in light varies from 10 or 12 mm near the ground to 20 
or 25 mm just below the first brauch. In etiolated shoots, the 
length of internode varies from 12 mm to 60 mm, but the usual 
length is 25 to 38 mm. The increased length of internode would 
account for less than the doubling of the normal length of the 
plant. Since plants have been grown in the dark to 15 times the 
normal length, it follows that, in an etiolated plant, there are many 
more internodes formed. In other words, light, in the case of the 
normal plant, inhibits growth, speedily setting bounds to its du- 
ration. The shoots of my earlier preparations that grew to such 
great hights in the dark were grown in opaque black paper cones 
or cylinders, the neig'hboring green shoots from the same rhizomes 
being left in the light. It was then supposed that these etiolated 
shoots were supplied with assimilated material from the green 
shoots, and that we had here the unusual case of a shoot in the 
dark nursed by a neighboring assimilating shoot. To test the value 
of this hypothesis, the green shoots of several pots were wholly 
cut away and the pots were set in the dark. T\ ithin a week 
three rhizomes sent up each a new shoot. These were attended 
and watched for 6 months, when all plants were still living and 
had reached hights respectively of 177 cm, 74 cm, and 75.5 cm. 
Beihefte Bot. Centralbl. Bd. XXXI. Abt. I. Heft 1. - 
