■^^■'^J Gee: Behavior of Leeches 283 



TABLE XII 



Influence of Magnesium Sulphate Upon the Duration in Seconds of 

 Swimming Responses Evoked by Repeated Contact Stimulation 



Much the same result was secured upon placing leeches in 

 water through which a vigorous stream of carbon dioxide gas 

 had been passed for about twenty minutes. Thus in leeches 

 carbon dioxide is at first accelerating in its action. Depression 

 of the leech comes quickly, but recovery takes place in a rela- 

 tively short time. 



8. Mono-Potassium Phosphate 

 This substance has been found to be one of the group pro- 

 ducing fatigue in skeletal muscle. The experiments of Lee 

 (1907) on the leg muscle of the cat show that at the beginning 

 of the test the contractions of the phosphate muscle were much 



