354 FRAGMENTS OF SCIENCE. 



Sound in air moves at the rate of 1,100 feet a second ; 

 sound in water moves at the rate of 5,000 feet a second ; 

 light in aether moves at the rate of 186,000 miles a 

 second, and electricity in free wires moves probably at 

 the same rate. But the nerves transmit their messages 

 at the rate of only 70 feet a second, a progress which in 

 these quick times might well be regarded as inordinately 

 slow. 



Your townsman, Mr. Grore, has produced by electro- 

 lysis a kind of antimony which exhibits an action 

 strikingly analogous to that of nervous propagation. 

 A rod of this antimony is in such a molecular condition 

 that when you scratch or heat one end of the rod, the 

 disturbance propagates itself before your eyes to the 

 other end, the onward march of the disturbance being 

 announced by the development of heat and fumes along 

 the line of propagation. In some such way the mole- 

 cules of the nerves are successively overthrown ; and if 

 Mr. Grore could only devise some means of winding up 

 his exhausted antimony, as the nutritive blood winds 

 up exhausted nerves, the comparison would be com- 

 plete. The subject may be summed up, as Du Bois- 

 Reymond has summed it up, by reference to the case 

 of a whale struck by a harpoon in the tail. If the 

 animal were 70 feet long, a second would elapse before 

 the disturbance could reach the brain. But the impres- 

 sion after its arrival has to diffuse itself and throw the 

 brain into the molecular condition necessary to con- 

 sciousness. Then, and not till then, the command to 

 the tail to defend itself is shot through the motor 

 nerves. Another second must elapse before the com- 

 mand can reach the tail, so that more than two seconds 

 transpire between the infliction of the wound and the 

 muscular response of the part wounded. The interval 

 required for the kindling of consciousness would pro- 



