200 The Philippine Journal of Science ms 
Table I . — Effect of successive stimuli on the time required for the spreading 
apart of the stigma lips of Martynia 
From the results it would appear that the first few stimuli 
have a beneficial effect in that they result in an increased rapid- 
ity of movement. This phenomenon is paralleled to some extent 
in the case of striated muscles of animals where repeated stimu- 
lation results at first in increasingly greater contractions. 
Beginning with the second or third stimulation, the stigma 
lips of Martynia spread apart, after closure, more and more 
slowly, thus showing a phenomenon resembling, at least superfi- 
cially, one phase of fatigue in the striated muscles of cold- 
blooded animals. In the latter, fatigue is characterized by a 
decrease in the force of contraction and an increase in the 
periods of both shortening and relaxing. 
Lee ® distinguishes between fatigue and exhaustion in animal 
muscles. According to this author, fatigue appears to be due 
chiefly to poisoning by fatigue substances ; exhaustion to the con- 
sumption of contractile material. The feeble response shown by 
the stigma lips of Martynia after a number of successive stimula- 
tions is superficially similar to exhaustion. A lack of knowledge 
of the mechanism of movement in Martynia makes it impossible to 
compare the phenomena observed in this case with those shown 
by animal muscles ; but from what is known of the mechanism in 
other plants it would seem probable that movement is due 
to entirely different causes in the two cases and that this 
would also be true of fatigue. There is little evidence for or 
against the formation of fatigue substances in Martynia; but 
® Lee, E. S. The nature of muscle fatigue. Proc. Am. Physiol. Soc. in 
Am. Journ. Physiology 2 (1899) 11. 
