112 TENDRIL-BEARERS. Cuap. IIL 
revolve in ellipses. The ellipses are gencrally very 
narrow, but sometimes approach to circles. I several 
times observed that the longer axis slowly changed its 
direction, which is of importance, as the tendril thus 
sweeps a wider space. Owing to this change of 
direction, and likewise to the movement of the stem 
towards the light, the successive irregular ellipses 
generally form an irregular. spire. I have thought it 
worth while to annex a tracing of the course pursued 
by the upper internode (the movement of the tendri] 
being neglected) of a young plant from 8.40 a.m. to 9.15 
p.M. The course was traced on a hemispherical glass 
placed over the plant, and the dots with figures give 
the hours of observation; each dot being joined by a 
straight line. No doubt all the lines would have been 
curvilinear if the course had been observed at much 
shorter intervals. The extremity of the petiole, from 
which the young tendril arose, was two inches from 
the glass, so that if a pencil two inches in length 
could have been affixed to the petiole, it would have 
traced the annexed figure on the under side of the 
glass; but it must be remembered that the figure is 
reduced by one-half. Neglecting the first great 
sweep towards the light from the figure 1 to 2, the 
end of the petiole swept a space 4 inches across in one 
direction, and 3 inches in another. As a full-grown 
tendril is considerably above two inches in length, and 
as the tendril itself bends and revolves in harmony 
with the internode, a considerably wider space is swept 
than is here represented on a reduced scale. Dutrochet 
