THE LAW OF LIKEXESS, AND ITS WORKING. 231 



contrary, which may attain a length of eighty feet, a much 

 longer interval will elapse before action of body follows on 

 nervous impulse, seeing that the nerve-impulse has a longer 

 distance to travel. Assuming that in such animals as the 

 whale the nerve-action travels at the rate of seventy or 

 eighty feet per second, it follows that in a large whale which 

 has been struck near the tail by a harpoon, a second or so 

 will elapse before the impulse is transmitted to the brain, 

 whilst another second will pass before the second impulse is 

 sent from the brain to put the muscles of the tail in action 

 for the purpose of retaliating upon the harpooner. In such 

 a case it is assumed that the brain of the animal will be the 

 nervous centre or station at which information is received, 

 and from which instructions are in turn telegraphed to the 

 various organs and parts of the body. In the actual details 

 of the case, however, it is probable that the spinal marrow 

 of the animal or some part of it would act as the " head- 

 office " for receiving and issuing commands. We know that 

 a headless frog will wipe off with one foot a drop of vinegar 

 that has been placed on the other, and in the absence of 

 the brain, we thus assume that the spinal cord may act as a 

 nerve-centre. 



Doubtless the spinal marrow discharges this function 

 naturally \ and in view of this latter supposition, the interval 

 between the reception of a blow and the muscular actions 

 of an animal would be of less duration than in the case we 

 have just supposed, where the brain is regarded as the 

 central station of the nervous system. As Professor Tyn- 

 dall has remarked, "the interval required for the kindling 

 of consciousness would probably more than suffice for the 

 destruction of the brain by lightning, or even by a rifle- 

 bullet. Before the organ (that is, the brain) can arrange 

 itself, it may therefore be destroyed, and in such a case we 

 we may safely conclude that death is painless." 



But confining ourselves to the domain of human thought, 

 it seems perfectly clear that the differences between persons 

 of different temperament are in reality referable in great 



