32 
Newcombe, Sensitive Life of Asparagus plumosus. 
have bent too for away from the eords to grasp them. The tips 
are now tied back to the cords. Thirty hours later both tips were 
found twining, one having niade 2 turns, the other 3 and one-half 
turns abonth the cords. It is evident therefore that the shoots 
were circumnntating yesterday, and began twining as soon as tied 
in position to do so. Possibly they would have twined the day 
betöre if they had been in proper position. 
Discussion. 
In the following discussion little time need be given to the 
consideration of the various activifcies of Asjjaragus plumosus which 
are similar to those of most orthotropic shoots. By reference to 
the experimental part of this paper, it will be seen that the aerial 
shoots of this plant, tili they reach a hight of 10 cm to 30 cm, 
are negatively geotropic and positively heliotropic, as are most 
plants. At least the extent of this study has not discovered im¬ 
portant differences. The negative thermotropism of the shoots has 
been observed but not followed in detail. It is the peculiar 
behavior of this plant in turning the upper part of its aerial shoot 
to the horizontal, as does Tropcieolum and Hedera helvx , that will 
here receive onr chief attention. 
I. Cause of Plaglotropic Position. 
In Miss Conover’s 1 ) paper, already referred to, very good 
evidence was given for regarding the plaglotropic position as due 
to diageotropism. This evidence, with my own added may be 
summarized here: 
The plaJotropic declination is not due to negative heliotropism; 
for, in the first place, the shoot remains positively heliotropic while 
it is bending and after it has reached the horizontal position; and, 
in the second place, seedlings raised in the dark will go to the 
horizontal position, and shoots always in the dark, grown from 
rhizomes, will decline toward the horizontal. 
The plaglotropic declination is not due to photonasty, for the 
same reasons as given in the last paragraph. 
The plaglotropic position is not due to geonasty. The usual 
test for geonasty is made by inverting the plant so as to bring 
the formerly upper side of the shoot below; or the formerly upper 
side of the plaglotropic shoot is put in the flank position. The 
convex side of the curve should then become still more convex, 
on the supposition that the resistance of geotropism is removed 
by this change of position. This test, made for. Aspäragus, has 
given no indication that the plaglotropic curve in this plant is 
geonastic. Moreover, Miss Conover found by revolving a plant 
on the horizontal klinostat, the orthotropic part of the shoot being 
horizontal and the plant having recently made the plaglotropic 
M Conover, Behavior of Asparagus plumosus toward Gravitation and 
Light. (Plant World. XYI. 1913.) 
