396, The Botanical Gazette. [October, 
Inter-twining of tendrils.:—That the tendrils of certain Passiflore 
respond to the contact of one another, and as a consequence form 
inter-twining coils, was shown in a previous article in this volume, p. 
123. In an extension of this work, some attention has been paid to 
the tendrils of Aficrampelis echinata (Muhl.) Raf. (Echinocystis lobata) 
Chas. Darwin says in regard to this plant:? “One of my plants bore two 
shoots near together, and the tendrils were repeatedly drawn across 
one another, but it is a singular fact that they did not once 
catch one another. It would appear as if they had become habituated 
to contact of this kind, for the pressure thus caused must have been 
- much greater than that caused by a loop of thread weighing only one 
sixteenth of a grain.” He adds, “I have, however, seen several ten- 
drils of Bryonia dioica interlocked, but they subsequently released 
one another.” ‘ 
The tenor of the paragraph is such that the reader is left to infer — 
that these organs possess such development of the contact sense 
to be able'to distinguish the contact of tendrils from that of other 
bodies. This inference is re-asserted in more positive form in many 
important physiological text books, and the writer would hesitate to 
offer evidence to the contrary, were not the facts so easily and readily 
apparent. 
It is of interest to know that the plants of Mic 
upon which Darwin’s observations were made, were 
sent him by Asa Gray, and the erratic behavior of the = 
of this representative of an American genus may be due to a¢ pen 
environment, and climatic conditions. Several plants of this weet 
growing in a.natural situation on the university campus, a ps, 
under observation for some time, and all exhibit numerous page ; 
of the inter-sensitiveness of the tendrils. If an active tendril is . 
touched on the sensitive portion of the ventral surface by wie a 
another tendril, it will form curves in thirty to seventy att drils po 
on any one plant can be seen all stages of inter-reaction; te sh pee 
be found that have recently made contact and formed ae pee 
haps forty degrees, others that have formed one OF pew pr 
the grasped portion, and others that have completed t + of mature 
thrown their own free portion into spirals after the pasa part of 
tendrils. Ifthe tendrils have come in contact at the sensi “ab pi 
both, the reactions in each will be similar. The size se e 
ness of the spirals show that they are functionally meer as ced it 
Less frequent examples of inter-twining have also ; — 
1Read before the Botanical Club, A. A. A. S., Madison meeting. 
*Climbing Plants, p. 131. 
rampelis echinata, 
raised from seeds 
drils 
