36 
Newcombe, Sensitive Life of Asparagus plumosus . 
this alternate declension and ereetion of the tip continues as long 
as the shoot continnes to grow in tlie dark, which may last for 
several months. This declension and ereetion of the tip is not 
mere ephemeral nutation. I conld not see that Asparagus increased 
its ephemeral nutation in the dark, as Maige 1 ) fonnd to he true 
for Stachys palustris and Mentha arvensis. Each of the larger 
declinations that the tip took was immediately controlled by gravi- 
tation as was demonstrated several tim es by displacing the shoots 
from that Position, and noting their quick return. There were also 
positions, divergent from the vertical, assnmed often for but brief 
periods, an hour, more or less. Whether in such a case plagio- 
geotropism had taken the tip to its position, i had no means of 
determining, except to remember that on the horizontal klinostat 
in the dark such nutation did not take place. 
By r'eference to that part of this paper entitled, „Behavior 
of Shoots exposed to Light for One to Several Days“, it will be 
seen that the effect of. light on the assumption and retention of 
the diageotropic position makes itself feit at a distance of several 
days, 8 days at least. This is evidenced from the fact that those 
shoots which were covered from the light 8 days, or less, before 
they made the plagiogeotropic decline, retained the plagiotropic 
position permanently and nnfolded their bfanches. Other shoots 
which were covered for a longer time before they made the decline, 
11 days or more, probably would have erected later, bnt the ex- 
periments were not continued long enongh to determine. Bnt 
since the branches had not begun to unfold, it may be inferred 
that the shoot had not come to its definitive growth. Both in the 
normally growing plants and in those growing in the dark, the 
beginning of the nnfolding of the branches was a sign that elon- 
gation of the main axis was abont to end. The formation of the 
plagiotropic enrve is thus a phase phenomenon, related to the phy- 
siological state, related to the approaching cessation of growth. 
Apparentfy, on the withdrawal of light, the Inhibition of growth 
is removed and there arises a contest within the plant itself, on 
the one hand, for ending growth and making the plagiotropic curve, 
and, on the other, for continuing growth. Temporarily one tendency 
gains the ascendency and temporarily the other, and thns the 
contest goes on indefinitely, but with the end-result favorable to 
growth; for the orthotropic elongation of the shoot in the dark is 
far in excess of the plagiotropic. In the case of seedlings, the 
exhaustion of stored food entails the cessation of growth in the 
dark. Whether the seedling shoots would make the plagiotropic 
bend in the dark, were there a continuing supply of food, we have 
no means of knowing. 
That light bears some part in bringing the aerial shoot growing 
from the rhizome to the full diageotropic position, thru changing 
the response to gravitation is illustrated by the behavior of such 
x ) Maige, Recherches sur les plantes rampantes. (Ann. Sei. Nat. Ser. 8. 
VII. 1900. p. 249.) 
