124 WHAT IS LIFE ? 



And lastly, when the brain sleeps, that is, when it 

 has a smaller supply of blood, when chemical reaction 



nerve of sensation be divided in its course to the brain, all the parts 

 which are supplied by it lose their sensibility for no other reason 

 than that the conducting of the impression to the brain is no longer 

 possible. Every man who has no knowledge of physiological pro- 

 cesses, believes the feeling of hunger to be in the stomach . This is 

 not so, the brain alone makes us conscious of the feeling. If the 

 nerve uniting brain and stomach be divided, hunger is at an end, nor 

 does it return. Neither does anger arise in the liver, or courage in 

 the chest, but in the brain only. The heart, to which in common 

 language so many feelings are ascribed, has nothing whatever to do 

 with mental actions. It is nothing but a hollow muscle, which 

 propels the blood. That mental feelings are indicated by its more 

 or less frequent pulsations is caused by the mediation of a nerve, 

 which connects heart and brain. This sympathy ceases with the 

 destruction of the nerve. We see not with the eye or the optic 

 nerve, but with the brain. If the optic nerve be divided, seeing is 

 at an end." ..." There have been a few instances of men in whom, 

 by some accident, a dislocated cervical vertebra compressed the spinal 

 cord in such a manner that the connection between the brain and the 

 body was severed. Respiration and pulsation continued, however, 

 and with them the nutrition of the brain. Such a state is a living 

 death. The whole body is perfectly insensible and motionless a 

 corpse ; the head only lives, with its immediate adjoining parts. 

 The intellect, however, remains in such persons intact ; they are 

 living corpses." ("Force and Matter," Dr. Louis Biichner, 1864, 

 pp. 143-147.) 



" That the spinal cord as a whole is a nervous centre admits of 

 very simple proof, on the lower and on the higher animals, and on 

 man. A decapitated frog having lost brain and bulb, reacts by 

 movements when the skin is pinched, and no longer reacts when the 

 spinal cord is destroyed. A man whose spinal cord is cut, say in the 

 dorsal region, by disease or by mechanical injury, reacts by move- 

 ments of his lower limbs when the soles of his feet are touched, and 

 he bears witness to the fact that he feels nothing, that he is not 

 conscious of any impression, i.e. that the reaction of the spinal cord 

 is carried out without sensation. Such reactions are instances of 



