432 Vines. — On Epinasty and Hyponasty. 
numerous leaves, the seven youngest showed themselves to be 
hyponastic by rising away from the surface of the soil ; the 
remaining leaves simply showed well-marked epinastic curva- 
ture and nothing more. The seven youngest leaves not only 
rose hyponastically, but they gradually assumed different 
positions according to their relation to the centre or axis of 
the plant. On the second day of the experiment — that is, after 
forty-eight hours in the horizontal position in darkness — their 
relative positions were as follows, the numbers used indicating 
the relative age of the leaves, No. 1. being the youngest. Leaf i , 
inserted vertically below the axis, showed strong hyponastic 
curvature so that it curved completely over the growing- 
point ; leaf 6, inserted almost directly beneath leaf i, had 
curved upwards so that its upper surface was nearly horizontal ; 
leaves 2, 5> and 7, were inserted above the axis, leaf 2 nearly 
vertically above it, leaf 5 obliquely on the left side, leaf 7 
obliquely on the right side ; these three leaves were slightly 
raised from the soil, but showed no other change of position ; 
leaves 3 and 4 were inserted laterally on the axis, almost 
opposite each other, and showed, in addition to hyponastic 
curvature, torsion through nearly 90°, so that a part of their 
upper surfaces faced the zenith. On continuing the observation 
twenty-four hours longer, the only change observable was that 
leaf 6 had risen slightly above the horizontal, and that the 
youngest leaves began to be involute in consequence of trans- 
verse hyponasty. As I have already proved that the young 
leaves of Plantago are not negatively geotropic, it is useless to 
attempt an explanation of these phenomena based on the as- 
sumption of negative geotropism : it is only necessary to 
ascertain whether or not they are explicable on the assumption 
of diageotropism. Taking first the leaves inserted below 
the axis, the position of leaf 1 can be satisfactorily accounted 
for by supposing that, at this early age, hyponasty is so 
powerful that it altogether neutralises diageotropism : in 
accordance with this, the position of leaf 6 is due to diminished 
force of hyponasty, a consequence of its being older than 
leaf 1, which can only so far counteract diageotropism as to 
