PRODUCED BY A CONSTANT CURRENT. 7 



Budge 1 , of Valentin 2 , of Schiff arid Herzen 3 , and of Lautenbach 4 . 

 Thus we have the employment of metallic instead of unpolarisable 

 electrodes ; no measures of precaution are mentioned as being used 

 to prevent escape of current from one circuit into the other ; ex- 

 periments are carried out on one and the same nerve in such a way 

 that the direction, as well of the polarising as of the test current, 

 is many times reversed ; and so on. Under such circumstances it 

 was impossible to arrive at clear and unambiguous results. Schiff 

 avows too ' that to bring together all tolerably similar results of ex- 

 periment would seem to produce a perfect chaos 5 ' 



Small as was the impression which the works I have mentioned 

 were able to make on Pfliiger's results, these were equally far from 

 being upset by the adverse conclusions obtained from experiments 

 on living human beings. Tick 6 found no change elicited in the 

 excitability of nerves by the constant current. Eulenburg 7 con- 

 firmed Pfliiger's laws. Erb 8 obtained at first quite opposite results, 

 but having had his attention directed by Helmholtz to the likelihood 

 of this having been caused by a peculiarity in distribution of the 

 current in the uninjured human body, he repeated his experiments 9 , 

 and now attained results completely agreeing with those of Pfliiger 

 and Eulenburg. Runge 10 on the other hand arrived at quite opposite 

 conclusions. It would seem pretty clear, however, that the com- 

 plicated, not to say undeterminable, conduction-relations which exist 

 in the living human body must cause a considerable difference 

 between these results and those which rest on experiments made 

 with isolated preparations of nerves, and that results of this kind 

 cannot be adduced against Pfliiger as proofs so long at least as 

 no question is taken into consideration excepting that of the way in 

 which the normal excitability of a nerve is changed by a constant 

 current of electricity. 



1 Budge, Archiv fiir patholog. Anatomie, xxviii, 1863, pp. 282-301. 



2 Valentin, Die Zuckungsgesetze des lebenden Nerven und Muskels, Leipzig, 

 1863, pp. 14, 65-86; Physiologische Pathologic der Nerven, i, Leipzig, 1864, 

 pp. 134, 135; Zeitscbrift fiir Biologic, viii, 1872, pp. 210-238; Moleschott's Unter- 

 suchungen, xi, 1873, pp. 169-181 ; Zeitschrift fiir Biologic, x, 1874, pp. 153-176. 



3 Schiff und Herzen, Moleschott's Untersuchungen, x, 1867, pp. 430-446. 



* Lautenbach (under Schiff's direction), Archives des sciences physiques et 

 naturelles, nouvelles pdriode, Ivii, 1877, pp. 88-99. 



5 Schiff, Moleschott's Untersuchungen, x, p. 436. 



6 Fick, Medicinische Physik, Zweite Auflage, 1866, p. 377. 



7 Eulenburg, Deutsches Archiv fiir Klinische Medicin, iii, 1877, pp. 117-142. 



8 Erb, ib. iii, 1867, pp. 271-273, and 513-524. 



9 Erb, ib. iii, pp. 525-528. 



10 Kunge, ib. vii, 1870, pp. 356-384. 



