136 EVOLUTION, OLD AND NEW. 



ties of the nerves, and are carried thence through all 

 the branches of the sensory system. This system forms, 

 as we have said, a whole, all whose parts are inter- 

 connected by so close a union that we cannot wound 

 one without communicating a violent shock to all the 

 others; the wounding or simply pulling of the smallest 

 nerve is sufficient to cause lively irritation to all the 

 others, and to put the body in convulsion ; nor can we 

 ease this pain and convulsion except by cutting the 

 nerve higher up than the injured part ; but on this all 

 the parts abutting on this nerve become thenceforward 

 senseless and immovable for ever. The brain should 

 not be considered as of the same character, nor as an 

 organic portion of the nervous system, for it has not the 

 same properties nor the same substance, being neither 

 solid nor elastic, nor yet capable of feeling. I admit 

 that on its compression perception ceases, but this very 

 fact shows it to be a body foreign to the nervous system 

 itself, which, acting by its weight, or pressure, against 

 the extremities of the nerves, oppresses them and stupe- 

 fies them in the same way as a weight placed upon the 

 arm, leg, or any other part of the body, stupefies the 

 nerves and deadens the perceptions of that part. And 

 it is evident that this cessation of sensation on compres- 

 sion is but a suspension and temporary stupefaction, for 

 the moment the compression of the brain ceases, percep- 

 tion and the power of movement returns. Again, I 

 admit that on tearing the medullary substance, and on 

 wounding the brain till the corpus callosum is reached, 

 convulsion, loss of sensation, and death ensue ; but this 

 is because the nerves are so entirely deranged that they 



