296 THE SO-CALLED SECONDARY ELECTROMOTIVE 



been expected, but, on the contrary gave to a certain extent opposite 

 ones ; these however confirmed our main law in a most striking and 

 instructive way. 



For these experiments I made use of a method of my own for 

 causing heat rigor in a tract of muscle 1 ; which du Bois-Reymond 

 has more recently described as the production of a * thermal cross- 

 section 2 .' The experiment naturally allowed the use of a single 

 muscle arranged as in the schema of that just described, a tract 

 in heat rigor taking the place of the tendon. The following 

 arrangement was however still better adapted for this ex- 

 periment. 



The two sartorius muscles were so prepared that they remained 

 attached to the symphysis. They were then placed together, 

 and the symphysis with the muscle attachments was dipped 

 8 mm. deep into hot water ; heat rigor being thus produced. The 

 muscles were then drawn apart and stretched out by fixing the 

 knee-ends with hedgehog spines to a cork board. The polarising 

 current was led in at the knee-ends, the leading-off contacts were 

 placed, one in the region of heat rigor (at the symphysis), the other 

 on the unimpaired surface of the same muscle in its upper half. If 

 the right muscle be thus led off, then the left one serves merely as 

 an indifferent conductor of the polarising current ; the muscle ex- 

 perimented upon is however the right one, in which the upper 

 polarising and upper leading-off electrodes are identified and lie on 

 the thermal cross-section. At the end of an experiment the other 

 muscle may be used by shifting the leading-off electrodes. The full 

 demarcation current is naturally led off and has to be com- 

 pensated. 



The preceding experiments would lead us to expect that the -f 

 phase of the after-current should only occur when the physiological 

 anode is united with one leading-off contact, or, in other words, 

 when the polarising current is directed from the muscle not led off 

 to the led- off one ; and hence is in this ' abterminal.' Instead 

 of this, the + phase never appeared under such circumstances ; 

 but sometimes appeared with the polarising current directed the 

 opposite way. 



The cause of this apparent discrepancy was clear to me. It is known 

 that Biedermann found that the breaking excitation failed in the case 



1 See Pfltiger's 'Archiv/ vol. iv. p. 167. 



2 ' Archiv f. Anat. u. Physiolog.' 1873, p. 526 (Ges. Abh. ii. p. 409). 



