402 



EFFECT OF IRRITATION OF A POLARIZED NERVE. 



lu the above experiment the desceiidiDg irritating current was kept 

 of the same strength throughout. In the beginning, while the ascend- 

 ing pohirizing current was weak, it produced an increased excitability 

 of the nerve. When, however, it was increased to "iheochord 53," Ptiil- 

 ger's result (i c, a diminished excitability) was obtained, which became 

 more marked when the polarizing current was increased to 1 cell. A 

 curious i)henomenon was observed which is to be seen, to a greater or 

 less degree, in all the experiments. In the beginning " rheochord 33" 

 produced an increased excitability of the nerve, while thirteen irritations 

 later it produced the opposite efte^ct. So it must be concluded that the 

 preparation becoming older causes the effect of a polarizing current of a 

 certain strength on the excitability of the nerve to change. This will 

 explain the result obtained by Schiff and Herzen. These investigators 

 found that while in the beginning of an experiment on the excitability 

 of polarized nerves tliey might obtain certain results, 15 or 30 minutes 

 later entirely different results were obtained. 



EXPERIMENT 187. 



Irritation alone. 



strength of the irritation. 



cent. 



1 Daniel 



Kheochord 691 



Kheochord 1308 



Eheochord 1214 



Kheochord 1000 



1 Dnniel 



Eluocliord 188 



IDaniel 



Height of 

 the con- 

 tractions. 



2 Daniel cells . 



1 Daniel . . . 

 Eheochord. 



.1009 



16.1 

 8.8 

 5. .5 



17.3 

 5.5 



13.2 

 3.8 

 3.8 

 3.8 

 4.2 

 2.1 

 5.1 

 1.6 



10,1 

 7.2 

 8.2 



18.9 



16.1 

 0. 



15.5 

 8.2 



12.1 



21. 



31.1 



10. 



14,9 

 0, 



oo 2 



16^5 

 33.5 

 37. 



7.2 

 12.1 

 29.4 

 28.6 



6.7 



6.4 



3.2 

 11.1 



3.2 

 29.9 

 29. 



8, 



4.4 



Irritation plus polarization. 



Strength of the constant 

 current. 



1 Daniel cell : 

 Eheochord 



.38 



1 Daniel 



Eheochord 38 



Eheochord 33 



Eheochord 38 



Eheochord 48 



Eheochord 56 



IDaniel 



Eheochord 38 



Height of 

 the con- 

 tractions. 



29.2 



28.4 



14.4 



24.3 



11. 



14.5 



3.8 



3.8 



3.8 



0. 



0, 



0. 

 , 0. 



0. 



0. 



4.9 

 10,2 

 12,6 



8,2 

 15,9 

 26.2 

 25.1 



8,2 



8,2 



8,2 



9,2 



7.8 

 14.1 



7.5 

 31. 



7.2 

 10,3 

 12. 1 

 14.3 

 14,1 

 22.1 



7,6 

 13,4 



8, 



3,5 



6,3 



0. 



0. 



0. 



Eemarks. 



A descending polarising 

 current 8™'". above a 

 descending irritating 

 current, 



Eaua temporaria 



