THE MECHANISM OF MOVEMENT AND TRANSMIS- 
SION OF IMPULSES IN MIMOSA AND OTHER 
“SENSITIVE” PLANTS: A REVIEW WITH SOME 
ADDITIONAL EXPERIMENTS. 
D. T. MACDOUGAL. 
(WITH PLATE XIII) 
THE history of investigation of the transmission of impulses 
in “ sensitive” plants begins with the work of Lindsay on Mimosa 
in Jamaica in 1790, which for some reason was not published 
until 1827.7 During the century following the subject received 
~ attention except that given it in the north temperate zone, 
in warm houses, and for the greater part under highly artificial 
conditions. In such manner it has been the object of numerous 
series of experiments, and of many highly ingenious specula- 
tions, 
Briefly summarized, the aggregate results of both methods 
embrace nothing beyond a delineation of the anatomical details, 
the chemical properties of some of the tissue systems, an 
mmense number of the features of reaction under artificial con- 
ditions, “working theories” of the mechanism of the motor 
°rgans and metaphysical explanations of the transmission of 
mpulses, and general relation of such highly specialized forms 
of sensitiveness to the developmental history of the plant. 
3 € work upon the subject under conditions necessarily arti- 
ficial has been so futile in real results that it has come to be 
admitted on all hands that asatisfactory solution of the problems 
Presented may be accomplished only by researches prosecuted 
= the tropics, in the habitat of plants which have acquired a 
high degree of sensitiveness. 
1 
“eo Jour. Sci, Lit. and Art 24:79. 1827, and 25: 434. 1828. 
293 
