Newcombe, Sensitive Life of Asparagus plumosus. 
33 
bend, tbat tbe bend was promptly straightened out. If geonasty 
were tbe effective agent in bending tbe tip in normal conditions, 
tben it ongbt not to be so readily overcome on tbe klinostat by 
autotropism. 
I see no reason for calling tbis horizontal bend geonyctonastic , 
as Czapek 1 ) applies this term to tbe bending of tbe flower stalk 
of Papaver and Sedum. 
Diageotropisin is tbe cause of tbe plagiotropic position. Tbe 
horizontal position is assumed by tbe tips of seedling sboots kept 
in tbe dark front tbe seed. Revolution on tbe horizontal klinostat, 
started wbile tbe young shoot is orthotropic, causes tbe development 
of tbe sboot to maturity in the orthotropic condition, witb all 
branches arranged radially and regularly spaced about tbe central 
axis. Miss Conover’s result by tbe use of tbe centrifuge is also 
significant; since sbe found tbat if plants witb young orthotropic 
sboots were kept on tbe centrifuge for several days, tbe tips of 
the sboots finally took a position parallel witb tbe axis of revo- 
lution, tbis position corresponding to tbe plagiogeotropic position. 
Altbo the sboot becomes diageotropic on the centrifuge, it 
remains negatively geotropic on tbe klinostat, wben revolved about 
its horizontal axis. As already noted, it migbt be tbot tbat tbe 
main axis or its lateral branches would become diageotropic on 
tbe klinostat, since tbey are, or could place themselves by a small 
bend, in tbe horizontal position, tbat is, parallel witb tbe axis of 
tbe klinostat. Tbat tbey do not thus develop diageotropism is 
evidence tbat tbe plant must be at rest in Order to give gravi- 
tation an opportunity to act for some time in tbe same direction 
on tbe cells wbicb are active in tbe process of reversing tbe 
response to gravitation. A plant wbose aerial sboot is in process 
of taking tbe diageotropic position may be reversed so as to place 
tbe formerly upper side downward. Tbe bent portion of tbe sboot 
is nninfluenced by tbis cbange of 180 °. But if tbe plant is re¬ 
volved on tbe klinostat so tbat tbe horizontal axis of revolution 
passes tbru tbe axis of tbe bent portion of tbe sboot, tbis bent 
portion being therefore in tbe horizontal position wbile revolving, 
tbe bent part goes back to tbe direction of tbe orthotropic portion 
of tb^ sboot. Tbis bebavior sbows again tbat, altbo tbe cells acted 
upon by gravitation in bringing in plagiogeotropism may lie witb 
any side directed toward tbe center of tbe earth, tbey must lie 
in tbe same position for a considerable time in Order to give gra¬ 
vitation a footing for action. 
II. The Plagiotropic Shoot remains Radial. 
Since tbe young sboot of Asparagus, wbile it is curving from 
tbe vertical to tbe horizontal, and still in a growing condition, 
may be inverted without cbanging tbe progess of tbe apical portion 
J ) Czapek, Geotropismus und Pflanzenform * (Wiesners Festschrift. 
1908. p, 92.) 
Beihefte Bot. Centralbl. Bd. XXXI. Abt. I. Heft 1. 
3 
