98 PROCEEDINGS OF THE AMERICAN ACADEMY 



durable electric cable, in which Professor Treadwell, Dr. C. T. 

 Jackson, Charles Jackson, Jr., Dr. H. E. Storer, Frank Storer, 

 and the Recording Secretary, took part. 



Professor Gray read the following " Note on the Coiling of 

 Tendrils." 



" As much as twenty years ago, Mohl suggested that the coiling of 

 tendrils ' resulted from an irritability excited by contact.' In 1850 he 

 remarked that this view has had no particular approval to boast of, yet 

 that nothing better has been put in its place. And in another para- 

 graph of his admirable little treatise on the Vegetable Cell (contributed 

 to "Wagner's Gyclopcedia of Physiology), he briefly says : 'In my opin- 

 ion, a dull irritability exists in the stems of twining plants and in ten- 

 drils.' In other words, he suggests that the phenomenon is of the 

 same nature, and owns the same cause (whatever that may be) as the 

 closing of the leaves of the Sensitive-plant at the touch, and a variety 

 of similar movements observed in plants. The object of this note is to 

 remark that the correctness of this view may be readily demonstrated. 



" For the tendrils in several common plants will coil up more or 

 less promptly after being touched, or brought with a slight force 

 into contact with a foreign body, and in some plants the movement 

 of coiling is rapid enough to be directly seen by the eye ; indeed, is 

 considerably quicker than is needful for being visible. And, to com- 

 plete the parallel, as the leaves of the Sensitive-plant, and the like, 

 after closing by irritation, resume after a while their ordinary expanded 

 position, so the tendrils in two species of the Gucurhitacece, or Squash 

 family, experimented upon, after coiling in consequence of a touch, will 

 uncoil into a straight position in the course of an hour ; then they will 

 coil up at a second touch, often more quickly than before ; and this may 

 be repeated three or four times in the course of six or seven hours. 



" My cursory observations have been principally made upon the Bur- 

 Cucumber (Sicyos angulatus). To see the movement well, full-grown 

 and outstretched tendrils, which have not reached any support, should 

 be selected, and a warm day ; 77° Fahr. is high enough. 



" A tendril which was straight, except a slight hook at the tip, on 

 being gently touched once or twice with a piece of wood on the upper 

 side, coiled at the end into 2^-3 turns within a minute and a half. 

 The motion began after an interval of several seconds, and fully half 

 of the coiHng was quick enough to be very, distinctly seen. After a 



