OF MOVEMENT IN PLANTS. 57 
compact and well formed if developed after contact. In each case the structural modi- 
fications are the same, i.e. the parts become hard, dry and woody.’ 
The figure described by the nutating tip is approximately ellipsoidal (Plate III), the 
major axis being transverse. This axis not infrequently reaches a length of 24 to 27 cm.; 
that of the minor axis being from 13 to 22 em. in length. In Æchinocystis lobota, the 
diameter of the figure, according to Darwin’, is even larger than this, measuring from 38 
to 41 em. While the tendril thus describes a figure, the vertical plane of which is 
parallel with the axis of the plant, the space through which the tip moves is greatly 
augmented by a supplementary movement in the growing end of the vine on which the 
tendril is found. This secondary movement causes the tendril to describe a double 
motion, which increases the possibility of its contact with surrounding objects.’ It is of 
short duration, however, since the movement of the vine is confined to the few internodes 
at the end, and at any one node continues for two days only after the tendrils are in 
motion ; so that, by the time the first arm of the latter has grasped a support, the move- 
ment of the vine at that particular node may have ceased entirely. So long as there is no 
contact the tendril continues to revolye, until a gradual increase of permanent tissue 
arrests its activity. 
Circumnutations do not belong to the tendril arms alone. Not only does the petiole 
of each tendril perform a definite circumnutation, but the leaves exhibit a similar movement 
in a marked degree, as demonstrated by G. E. Cooley during the past summer. The 
motion of the tendril petiole is best observed by Darwin’s method of a fine glass filament 
with a small black bead at its extremity, inserted into the end of the petiole where the 
arms separate. The circumnutation of the leaf is to be determined from its tip, as in 
tendril motion. In this manner, we have obtained, from a leaf of medium size, a figure 
of twenty different changes of direction, within the space of three hours. The movement 
was found to be much slower, and the figure much smaller than in the case of the tendrils. 
This, however, would appear to be the case from theoretical considerations, when we 
compare the structural features of the two and have due regard for the difference in size. 
The figure described by the leaf, so far as formed, was quite regularly ellipsoidal, though 
the curve was retraced before the ellipse was fully completed, in all of these respects 
showing striking similarity to the movement of the tendril. 
During a series of observations extending over a period of nearly one week and 
embracing both day and night, almost the entire circumnutations of each tendril observed 
were secured. Temperature and other conditions were noted at each of the observations, 
which were taken at intervals of from two minutes to one hour, according to the 
condition of activity. The following are the results :— 
Tendril No. 1.—Aug. 12th, at 9.30 a.m., one of the longest arms was selected after it 

! My observations confirm those of Darwin with regard to other members of the Cucurbitaceæ, that when 
a spiral develops freely, it is always simple; that it only reverses when the tip is attached to a support. 
* Climbing Plants, 128, ete. 
’ The fact that there is this double motion as a result of tendril vine action, shows that the true figure is to 
be obtained only when the tendrils revolve about the inner surface of a glass globe and the changes of direction 
are recorded from the outside. This, however, was not practicable in our case, nor was it essential to the accuracy 
of the conclusions to be obtained, For our purpose, the plane recording surface was amply sufficient. 
Sec, IV., 1886. 8, 
