53 o THE POPULAR SCIENCE MONTHLY. 



suffer, very curiously, a complete loss of hair ; they are affected with 

 paralysis, dumbness, deafness, amaurosis, or imbecility. In brief, the 

 destructive attacks of atmospheric electricity touch all the functions of 

 the nervous system. 



The action of electric fishes may be likened to that of lightning, in 

 being independent of our intention. The shocks of the gymnotus are 

 particularly formidable. Alexander Humboldt relates that, having 

 put both his feet on one of these fish, just taken from the water, he ex- 

 perienced so violent a shock that he felt pains in all his joints the rest 

 of the day. These shocks throw the strongest animals down, and it is 

 necessary to avoid rivers frequented by the gymnotus, because, in at- 

 tempting to ford them, horses or mules might be killed by the dis- 

 charges. To capture these fish the Indians drive wild horses into the 

 water, stirring the eels up out of the mud by their trampling. The 

 yellowish livid creatures press against the horses under their bellies, 

 throw down the greater part and kill some of them, but, exhausted in 

 their turn, they are then easily taken with the aid of small harpoons. 

 The savages employ them to cure paralysis. Faraday compares the 

 shock of a gymnotus, which he had an opportunity to study, to that of 

 a strong battery of fifteen jars. A live eel out of water, when touched 

 by the hand, communicates a shock strong in proportion to the extent 

 of surface in contact, and the stroke is felt up to the shoulder, and fol- 

 lowed by a very unpleasant numbness. It may be transmitted through 

 twenty persons in a chain, the first one touching the back, and the last 

 the belly of the eel. The fishermen discover the presence of an eel in 

 their nets by experiencing a shock in throwing pailfuls of water on, 

 to wash them. Water is a good conductor, and this fish kills or be- 

 numbs the animals it feeds on by delivering a discharge through the 

 water. 



Other sources of electricity are known to exist, besides thunder- 

 storms and fishes. Friction-machines, batteries, and induction instru- 

 ments, yield three kinds of currents that act on vital functions, some- 

 times in a similar way, but oftener with marked differences, which have 

 only recently been clearly distinguished. The action of static electri- 

 city, and that of electricity of induction, more sudden and violent, is 

 particularly marked by mechanical effects so striking that they have 

 long distracted experimenters from examining with due attention those 

 effects of another sort, produced by the galvanic current. Yet, the lat- 

 ter in reality affects the animal tissues in a deeper way, and its result- 

 ing phenomena deserve the liveliest interest from a theoretical point 

 of view, as well as from their applied uses. 



Dutrochet proved, by remarkable experiments, that, when a tube 

 closed below by a membrane, and containing gum-water, is placed in 

 a vessel containing pure water, the level of the gum-water rises little 

 by little through the gradual introduction of pure water into the tube, 

 while a certain quantity of the gum-water inside mingles with the 



