. \mphicarpcea monoica. 



It is not the intention todiscuss herein detail, the various 

 theories which have been advanced concerning the behav- 

 ior of the twining stem, the phenomenon of its circumnu- 

 tation, and their probable relations. 



Von Mohl, Palm, Darwin, Dutrochet, De Vries, PfefTer, 

 Sachs, Kohl, Noll, and other authorities have contributed 

 to the literature dealing with these problems. To a cer- 

 tain extent most of them believe that the peculiar manifes- 

 tations of the movement are due to variations of turges- 

 cence in the growing cells. Numerous hvpotheses have 

 been advanced to explain the movement. 



Dutrochet suggested that twining steins possessed pro- 

 perties peculiar to themselves, but his efforts to theorize 

 concerning their activity are not particularly lucid. Von 

 Mohl, and later, Kohl, asserted their belief that twin- 

 ing plants are endowed with irritability. More recent 

 authors concur in this opinion. The stimulus afforded by 

 contact with the support is of vast importance in causing 

 the continuance of the normal twining activity, and the 

 health and vigor of the plant is doubtless dependent upon 

 the successful manifestation of its habit of growth. Ex- 

 ternal conditions too have a decided influence upon the 

 behavior. The force of this statement will be evident as 

 the results of experiments are presented. 



Plants of the species under investigation twined readily 

 around a rough or smooth stick, varying from one-quarter 

 to three-quarters of an inch in diameter ; also around glass 

 rods, string, or wire, and if nothing else was available, 

 they utilized each other. Amphicarpua twines in dextrose 

 fashion — against the sun. 



Darwin's experiments recorded in " Climbing Plants," ' 

 though numerous and embracing many plants and repre- 

 sentatives of many orders, seem to the writer to lack cer- 

 tain essential requisites of information. Much of the move- 

 ment exhibited is unquestionably due to the innate char- 

 acteristics of the species. This again is modified by the 

 height and vigor of the individual under observation. 



