384 AVERS. [Vol. VIII. 



Frog where the weak flexor group is able under influence of 

 weak stimuli to overcome the stronger extensor muscles : but 

 with the increase in strength of the stimulation the extensors 

 gain the advantage and flexion gradually passes into extension. 

 Whether in either case the flexor muscles suffer any loss in 

 the intensity of their stimulation during extreme stimulation 

 of the antagonistic groups has not been determined, but it is 

 probable that they are the more stimulated the greater the 

 excitation of the flexors in order that the proper muscular 

 control may be maintained at all times. 



The following tables will serve to illustrate the important 

 variations in the response made by the laryngeal muscles to 

 electrical stimuli in all the Frogs experimented upon. The 

 opening following the increase in rate in Exp. XIX is unusual 

 but occurred several times in the course of the work. As to its 

 cause no clue was obtained. A tetanizing current applied to 

 the laryngeal nerve, when it produces opening of the glottis 

 does not suffice to produce a continued opening, for the glottis 

 soon returns to closure with all the muscles strongly contracted. 



After describing the experiments on the leg muscles, the 

 results of the two sets of observations will be compared and 

 their relation to Hooper's and Wedensky's results pointed out. 



In the experiments on the antagonistic muscles of the Frog's 

 leg constant care was taken to have the nerves as nearly 

 normal as possible. Through a cut in the skin of the leg, 

 the peroneal and tibial nerves were severed or else the sciatic 

 trunk was taken higher up and either separated into its 

 component peroneal and tibial branches or stimulated as a 

 whole. As a rule however the former method was employed 

 for it served to modify the conditions in an important way 

 from those adopted by Ellis in his experiments with the " ether 

 effect," for it allowed of absolute separation of the stimuli sent 

 into the two sets of muscles whether sent in simultaneously or 

 consecutively and permitted the experimenter to change at will 

 the rate or intensity, or both, of the stimulus to either set of 

 muscles. In part of the observations the leg was suspended 

 in a cuvette in water or salt solution, in others it was fastened 

 by means of the femur to a "frog board" and allowed to hang 



