OF MOVEMENT IN PLANTS. TA 
the foreign body is in contact; and even for a few seconds after its removal. Puncture 
with a pin, or the action of a loop of thread, produces similar effects. Irritation over a more 
extended area causes a correspondingly larger curvature. There is no special evidence in 
such cases that the impulse has been conveyed beyond the limits of the area irritated, 
and soon after the irritant body is removed—the growth in the various tissues having 
become gradually restored to its normal condition—the tendril straightens out and once 
more resumes its circumnutations. 
More violent mechanical stimuli produce a different effect, however. A sharp blow, 
such as would be given by a pencil, falling upon any part of the arm, produces an effect 
which throws the latter into a series of long undulations for its entire length. Prolonged 
irritation at the tip will usually produce the same effect. These facts at once and directly 
point to the inference that, while the effect is slowly produced, there is, nevertheless, a 
distinct transmission of impulse to very remote parts. Were concussion alone concerned, 
it might be possible to refer the whole change to it alone, as directly affecting the turgidity 
of the collenchyma tissue; but the fact that prolonged irritation will produce a similar 
result, should raise a question on this point. From what we now know concerning the 
sensitive nature of protoplasm, the relation which this substance bears to growth and 
turgidity, and its now well established continuity through living tissues, are we not 
justified in the belief that such transmissions as above noted are primarily propagated 
through this means ? 
CIRCUMNUTATION.—Our attention is first of all called to the fact pointed out by 
Darwin, and confirmed by our own observations, that the “tendrils revolve by the 
curvature of their whole length, excepting the sensitive extremity and the base, which 
parts do not move, or move but little.” This clearly shows that whatever force is in 
operation, acts uniformly through the entire length of the motile organ, and that the 
movement has not a local origin at or near the base. We must, therefore, conceive, 
as both Darwin’ and Sachs’ explain, that there is a longitudinal band of more actively 
growing tissue which extends from base to tip, and thus the arm is bent over toward the 
side of less active growth. So far, our own observations are in strict harmony with these 
views, but they do not accord with the opinion that these bands “travel round the tendril 
and successively bow each part to the opposite side.” As already shown, the figure 
described is not one of regular progression through successive points of an ellipse or other 
figure. (See Plate III.) In fact, the tip may change its direction very abruptly, often 
retracing the path just passed over (Nos. 36, 37 and 38), or the change may be less abrupt. 
While, therefore, it appears from the general equality of dextrorse and sinistrorse movement, 
that the totality of motion in one direction must be compensated by an equal movement 
in the opposite direction, the facts cited show quite conclusively that the band of growth 
does not pass regularly through successive points in the circumference, but that it arises 
irregularly. Again, the relations of the tissues in their mutual tension, and the position 
which the vibrogen tissue occupies, more especially the relation which this latter bears 
to the latitudes and departures of movement as already pointed out in a preceding 
paragraph, serve as a most important indication of the true position occupied by the bands 


2 Thid, * Text-book, 
1 Climbing Plants, 170. 
