45 
Must, therefore, all inhibition-processes be ascribed to synchronous 
competing influences? For this purpose a separate investigation into 
each phenomenon is necessary. I should like to touch upon one more, 
viz. the inhibitory influence upon the function of the heart through 
vagus stimuli. In 1845 the phenomenon was for the first time 
described by the Weer brothers. Of this Grey says: “Mais quelle 
est la nature intime de cette action? On dit que c'est un phénomene 
d'inhibition ou d’arrét. Jusqu’a la découverte des frères Weger l'idée 
d’excitation fut en physiologie étroitement liée a celle de mouvement ; 
apres cette découverte il fallut bien admettre que l’excitation d'un 
nerf centrifuge peut arréter un mouvement. Alors la notion des 
phénomenes d’arrét s’étendit peu a peu et elle établie anjourd’hui sur 
de nombreuses preuves. Mais nous ignorons toujours en quoi consiste 
exactement l’action inhibitoire’. If this heart-inhibition is to be con- 
sidered in the same manner as the above inhibition-processes, then 
there would have to be present two simultaneous motor impulses 
too. Rosrnzweic, Borrazzi and GaskELL showed that in the auricle 
of the tortoise there is a muscle-layer directly beneath the endo- 
thelium, quite different from the rest of the cordiac muscle. By 
stimulation of the vagus the slow, rhythmical contraction of this 
muscle is intensified, while the rest of the ecordiac muscle is 
weakened in its action. And, on the contrary stimulation of the 
sympathetic accelerates the heart action and inhibits this involuntary 
muscle-layer. Here therefore the inhibitory influence upon the heart 
by means of simultaneous efferent stimuli, exists in the same manner 
as in the case of the bladder function, the knee jerks etc. May we 
then assume the same for higher vertebrates? Here the circumstances 
are different, for we miss a so distinctly developed muscle-layer 
beneath the endothelium. 
But it is however known that there exists another muscle-layer 
besides the cordiac muscle, viz., the bundle of His-Tawara, which 
is found beneath the endothelium and ends in the fibres of Purkinje. 
In order to ascertain whether this bundle can contract the 
hearts of just previously slaughtered sheep were brought from the 
abattoir to the laboratory in their blood and warmly packed, on 
three occasions. In the laboratory a piece of cordiac muscle was 
immediately removed and placed in a chamber of ENGELMANN through 
which flowed defibrinated serum, previously oxygenated and kept at 
a temperature of 37° C. By means of an electrical stimulus a 
definite contraction in the cordiac muscle could be observed in this 
way. In two of the three cases it appeared histologically that a few 
cordiac muscle fibres were still present, but in the last experiment 
