688 



SCIENCE. 



[N. S. Vol. XX. No. 516. 



When the strength of fm. is used the activity 

 of the ganglion stops short at once, or a few 

 diminutive beats separated by greatly pro- 

 longed diastoles precede the complete aboli- 

 tion of the activity. In weaker concentra- 

 tions the depressor actions on the ganglion 

 cells appear only in diminished rate and 

 amplitude of the contractions in the reacting 

 portion of the heart. After complete aboli- 

 tion of the activity of the ganglion by CaCl, 

 the normal activity can be restored by bathing 

 with plasma, sea water or isotonic sodium 

 chloride solution. The resumption of func- 

 tional activity is very gradual. 



The action of calcium chloride on the gan- 

 glion is almost duplicated by that of CKsium 

 chloride, only that the latter salt does not 

 appear to depress quite as strongly as the 

 former. The recovery of function is also 

 somewhat quicker after the csesium chloride 

 bath. At fm. concentration caBsium chloride 

 stops the activity of the ganglion almost at 

 once, but in concentrations represented by 

 one part of fm. of the salt to ten or twenty 

 parts of sea water or plasma the depressor 

 action appears in diminished rate and ampli- 

 tude of the beats. The depressor action of 

 this salt on the ganglion cells is further shown 

 by its antagonism to the stimulating action 

 of the alkaloids veratrin, aconite, niconite and 

 digitalin. The addition of caesium chloride 

 to the solutions of these drugs greatly de- 

 creases their stimulating power, and bathing 

 the nerve-cord in isotonic (or even weaker) 

 solutions of the chloride after previous appli- 

 cation of the alkaloid solutions quickly 

 counteracts their stimulating effects. 



The most powerful stimulants to the gan- 

 glion cells are the chlorides of barium, potas- 

 sium and rubidinum. It is very difficult to 

 work with the chloride of barium because of 

 the fact that the barium is precipitated by 

 the sulphates in the plasma or sea water. The 

 isotonic solution of the salt can not, there- 

 fore, be diluted with either sea water or 

 plasma, but a dilution is necessary to study its 

 effect on the ganglion cells because the fm. 

 concentration stops their activity instanta- 

 neously. This is due to over stimulation or 

 paralysis. The barium chloride solution was 



diluted with a rnixture of fifteen parts of fm. 

 NaCl to one part | m. CaCh. This mixture 

 proved nearly neutral for the nerve-cord. 

 The addition of even one part of barium 

 chloride to twenty parts of this mixture pro- 

 duced a marked augmentation of the rate and 

 streng-th of the beats, which under the con- 

 ditions of the experiments meant an augmen- 

 tation of the rate and intensity of the nervous 

 impulses reaching the muscle. Rubidinum 

 chloride stimulates the nerve-cord at a dilu- 

 tion represented by one part of the fm. solu- 

 tion to twenty parts of sea water or plasma. 

 The isotonic solution of the salt stops the 

 activity of the ganglion instantaneously. 



The fm. solution of the chloride of potas- 

 sium stops the activity of the nerve-cord at 

 once, just like the similar solutions of the 

 chlorides of barium and rubidinum. Even at 

 the dilution of one part of the potassium 

 chloride solution to five parts of sea water or 

 plasma the activity of the ganglion is usually 

 arrested immediately, that is, without pre- 

 vious stimulation. That this is not a true 

 depressor action is shown by the fact that at 

 greater dilutions a strong stimulating action 

 appears. At a concentration of one part fm. 

 KCl to twenty parts of plasma the rate and 

 strength of the beats are greatly augmented 

 and this stimulating action is maintained for 

 a relatively long time. Potassium chloride is 

 a much greater stimulant to the nerve-cord 

 than is sodium chloride. The concentration 

 of the latter salt, represented by one part 

 fm. NaCl to twenty parts of sea water or 

 plasma, has no appreciable effect on the 

 nerve-cord. Yet under some conditions potas- 

 sium chloride appears to have a true depressor 

 action. When the ganglion has been bathed 

 for some time in a solution of one part f m. 

 K.Cl to twenty parts of sea water and this 

 solution replaced by sea water for some min- 

 utes, a reapplication of the former solution 

 to the ganglion may result in a partial depres- 

 sion of the activity preceding the stimulation. 

 The action of the potassium ion is thus a 

 complicated one and in part determined by 

 the condition of the ganglion cells. 



Application of distilled water to the nerve- 

 cord causes great acceleration of the rate of 



