same substances benumbs and paralyzes the muscular action. Immer- 

 sion in oxygenated muriatic acid restores to the exhausted parts the 

 power of being affected by the stimulus. Humboldt has observed, that 

 the season of spring, as well as the youth of the frog, was favourable to 

 the production of the phenomena: and that the fore feet of these creatures 

 with which the male fixes himself on the back of the female, by pressing 

 her sides, are more excitable than the hind feet; whilst in the other sex, 

 it is the hind feet that are the most susceptible. Halle ascertained, by 

 experiments made at the School of Medicine in Paris, that the muscles 

 of animals killed by repeated shocks of an electrical battery, receive an 

 increase of galvanic susceptibility; that this property subsists, without 

 alteration, in animals dead of asphyxia, or killed by immersion in mer- 

 cury, pure hydroden gas, carbonated hydrogen, oxygenated muriatic 

 acid, and sulphureous acid gases, by strangulation, by privation of air in 

 an exhausted receiver; that it is weakened after suffocation by drowning, 

 by sulphurated hydrogen, azote, and ammoniacal gas, and absolutely de~ 

 stroyed by suffocation in the vapour of charcoal. Spring is the season 

 in which galvanic experiments succeed best; an excess of life seems, at 

 that time, to animate all beings: it is accordingly at this epoch, that the 

 greater part of them are employed in the reproduction of their kind. 



CLXXII. Galvanic susceptibility disappears in the muscles of warm' 

 blooded animals, as the vital warmth goes off. Sometimes even, when 

 their life has ended in convulsions, their contractility is gone, though 

 there be still warmth, as if this vital property were exhausted by the con- 

 vulsions of death. In the cold-blooded, susceptibility is more permanent: 

 long after separation from the body, and even to the moment when pu- 

 trefaction begins, the thighs of frogs are affected by galvanic excitation; 

 no doubt, because, in these animals, irritability is less intimately con- 

 nected with respiration, because life is less one, is more divided among 

 different organs which have less need of action on each' other to produce, 

 its phenomena. 



Contractility is then, as I have shown in another work, too fleeting in 

 the human body*, to enable us to derive from galvanic experiments on 

 it after death, any light on the greater or less weakening of this vital 

 property in different diseases. Those authors who have maintained that 

 galvanic susceptibility is sooner extinct on the bodies of those that die of 

 scorbutic affections, than of those that die of inflammatory diseases, have 

 suggested a probable conjecture, which cannot, however, be established' 

 on experiment. 



Dr. Pfaff, Professor in the University of Kiel, who, next to Humboldt, 

 of all the scientific men of Germany, has attended most successfully to 

 experiments on galvanism, has had the goodness to communicate to me 

 the following facts. 



The galvanic chain produces sensible actions, that is to say, contrao 

 tions, only at the moment in which it is completed, by establishing a 

 communication among its parts. After it is made, that is, during the 

 time that the communication remains, all appears tranquil; yet the gal- 

 vanic action is not suspended. In fact, excitability appears singularly- 

 increased or diminished in the muscles that have been left long in the 

 galvanic chain, according to the variations of the reciprocal situation of 



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