CHEMICAL RKACKNTS ON LONCITUDINAL RESPONSE 1 35 



relaxation, by lines downward. Owing to the predominance 

 of this relaxing tendency, it will be seen that true contrac- 

 tile movement is here very much diminished. Even after 

 the relaxation has attained its 

 maximum, the responses remain 

 insignificant. When the speci- 

 men is not too long etherised, 

 the blowing in of fresh air 

 brings on gradual restoration. 

 It may be mentioned here that 

 ether also produces relaxation 

 of animal tissue. 



Explanation of anomalous 

 effect of ether on Mimosa. — 

 This experiment on the effect 

 of ether affords a very satis- 

 factory explanation of a phe- 

 nomenon in the recovery of 

 Mimosa, which has hitherto 

 been regarded as anomalous, 

 the leaflets is generally regarded as one of sensitiveness ; but, 

 when they have just closed, in consequence of stimulation, 

 if they be subjected to ether-vapour, they open out. Though 

 now, however, mimicking the appearance of sensitiveness, 

 they are in fact over- relaxed, a condition which is one of 

 relative insensitiveness. The explanation may be gathered 

 from the record in fig. Ji. It is necessary here to give 

 specific meanings to certain terms which have been used 

 somewhat indefinitely. We know that stimulation causes 

 the fall of the leaf, by differential contraction, and that the 

 organ recovers, or 'relaxes,' into its original form after a period 

 of rest. This term ' relaxation,' then, may be properly used 

 as the converse of ' contraction.' But, in consequence of the 

 expulsion of water from the organ after stimulation, it becomes 

 flaccid, and this condition also is sometimes vaguely described 

 as ' relaxed.' In my own use of the word, however, I shall 

 confine myself to denoting by it that process which is the 



Fig. 72. Effect of Ether 



Arrow marks moment of application. 

 This produced relaxation and 

 depression of response. Air 

 substituted at x , and there is 

 subsequent recovery of response. 



The outspread position of 



