o 



38 PRESENT STATE OF OECrANIC ELECTRICITY. 



from one moment to another, the excitation being greater the 

 greater and quicker the variations in a given time." * This 

 law is also illustrated by the so-called secondary contractions, 

 which are produced by bringing the nerve of the prepared 

 frog's limb into contact with a muscle during its contraction. 

 If the nerve is laid upon a muscle which is in a tetanic condi- 

 tion, however produced, the muscles of the limb become 

 tetanised also. This secondary tetanus is the result of that 

 alternating negative variation which the ordinary muscular 

 current undergoes during continued contraction. 



The nerves of sensation, like those of motion, are more 

 particularly affected at the closing and opening of the circuit, 

 and by variations in the current ; but they would also appear 

 to be capable of excitement by a constant current.-]- 



The organised heing may he considered electrically as pre- 

 senting a system of electrical currents, excited hy arrangements 

 in the system of its fluids, textures, and organs ; the tioo systems 

 representing each other. The electric disturbances and currents 

 in the Microcosm are represented by similar but grander phe- 

 nomena in the Macrocosm. These phenomena coincide in 

 both cases with the disposition of component parts, and rank 

 with other forms of material force alternately as causes and 

 effects. But the organised being is, moreover, subordinated 

 to those indwelling psychical powers and impulses by which 

 it enjoys its prescribed freedom. 



The Successive Opinions which have hcoi entertained regard- 

 ing the Action of the Electric Organ. — Walsh concluded that 

 the electricity of the Torpedo is entirely due to the batteries ; 

 that their upper and under surfaces are capable, from a state 

 of electric equilibrium, of being instantly thrown, hy a mere 



* Untersiichuiigen, vol. i. p. 258. + Ibid. p. 283. 



t In the report, as originally printed, a description of the special electrical 

 apparatus in certain iishes is then given ; but, as it is substantially the same 

 as that related in the preceding paper, it is not considered necessary to repro- 

 duce it. — Eds. 



