developed by Muscular Contraction. 59 



of the experimenter. If it is made but slightly sensible, it 

 only indicates powerful phsenomena ; if it is made very deli- 

 cate, it obeys the slightest perturbating causes. It is not im- 

 possible that a large number of experiments upon the currents 

 in animals and vegetables may merely arise from illusions, and 

 that what is attributed to animal and vegetable currents, may 

 be nothing more than the action of liquids upon the plates of 



f;old or platinum of galvanoscopes, or upon other different 

 iquids. If the two plates of gold of a galvanoscope are in- 

 serted in any direction in a potato which has either budded 

 or not, in an apple, or a cabbage-stalk, or the flesh of beef; 

 if any two parts of the skin, slightly moist, are touched with 

 these same plates, we have currents; if first one and then 

 the other plate be withdrawn in succession, and after having 

 washed and wiped it, it be replaced, the current is reversed ; 

 if the plates are more or less deeply immersed, reversions may 

 also occur. 



It is possible that the convulsions experienced by the frog 

 from the contact of the crural nerves with the muscles of the 

 legs, may depend only upon the heterogeneity of the liquids 

 which moisten these parts. It is possible that the permanence 

 of the direction of what is called the current of the frog may 

 be owing to a different alterability of the extremities of the 

 animal by the various solutions employed in these experiments. 

 In the experiment as arranged for determining the true or 

 false current in the frog, we merely require to substitute for 

 the animal a cord of thread impregnated with common salt, 

 and one of the ends of which has been touched with the stopper 

 of a bottle of sulphuric acid, and the other with the stopper 

 of a bottle of nitric acid, to reverse the current a great many 

 times, as is done in the case of the current of the frog. 



There is one experiment upon this subject which would 

 have a certain value without being decisive, it is that of the 

 action of a circuit of frogs upon a magnetic needle. 



I arranged a chain of frogs in the same manner as the pairs 

 of a voltaic pile are arranged ; this chain traversed a bell-glass, 

 beneath which a very delicate astatic needle was suspended. 

 I did not observe any distinctly-appreciable effect at the mo- 

 ment at which 1 united or separated the extremities of the 

 chain. Had an effect been obtained, the objection of the ac- 

 tion of the heterogeneous moist parts would still remain. 



It does not appear to me that the existence of electric cur- 

 rents in frogs and plants is a perfectly proved fact. I speak 

 openly, submitting my doubts to those philosophers who have 

 made most interesting, and in some cases very ingenious ex- 

 periments upon this subject. 



