377 



and increase the heart's action as decidedly as it had previously 

 lowered it ; while at an intermediate period it may seem to have no 

 influence at all. This principle gives the clue to understanding 

 what had before appeared incomprehensible in these experiments, 

 showing that facts which at first seemed utterly inconsistent, were 

 really perfectly harmonious. The case before related, in which re- 

 vival of the heart's action resulted from powerful stimulation of the 

 vagus, which, had the organ been contracting as usual, would have 

 arrested its movements and probably finally destroyed them, will 

 now be understood. I have seen other analogous cases of revival of 

 action by very powerful galvanism, which under ordinary circum- 

 stances would have arrested it, viz. twice in the heart and twice in 

 the intestines. The observation published so long ago as 1839 by 

 Valentin*, that mechanical or chemical irritation of the vagus in 

 the neck of an animal recently dead, and with the nerves conse- 

 quently enfeebled, causes contraction of the ventricles, admits of a 

 similar interpretation, as also does a corresponding fact regarding the 

 splanchnic nerves, given without explanation by Kupfer and Ludwig, 

 in a paper just published f, viz. that they lose their inhibitory in- 

 fluence a certain time after death, and acquire a motor power over 

 the intestines. 



Two more experiments require mention, as they exclude the 

 possibility of the agency in them, of either the vagi or the part of 

 the brain from which the vagi spring, having been performed upon 

 decapitated rabbits. In one of these cases, the carotids having been 

 tied near the head, the neck was completely severed behind the first 

 vertebra, care being taken to avoid haemorrhage from the vertebral 

 arteries, and artificial respiration, for which provision had been 

 made, was carried on for an hour and a half after decapitation. 

 The results of moderate galvanism, applied to the posterior dorsal 

 region of the spine, to which the poles had previously been attached, 

 were at first not distinct, but afterwards decided increase of action 

 was produced by it when applied at intervals during half an hour ; 

 the effect being perfectly apparent in the heart which lay exposed 

 before me. Exhaustion of the nervejs concerned having then taken 



* Valentin, De Functionibus Nervorum, p. 62. 



f Henle and Pfeufer's Zeitschrift, 3rd series, vol. ii. pt. 3. 



