PHYSIOLOGY. 119 



therefore, the vital power of the solid is restored before the 

 fluidity of the blood, which is a proof of the existence of nervous 

 power previous to any motion in our other fluids." 3. The 

 nervous fluid subsists in the nerves and muscular fibres long 

 after they are separated from the brain, and often when cut 

 into many small parts. 4. Though it be true that the brain 

 is a secretory organ, the fluid secreted may be destined to 

 another purpose ; and, so far as we understand that purpose, 

 the fluid fit for it must be unfit for the purpose of sense and 

 motion. 5. There is no appearance, in any part of the nervous 

 system, of provision made for an occasional accumulation of the 

 secreted fluid ; nor is there any evidence of its actually taking 

 place. 6. The phenomena of sleep and waking do not corre- 

 spond with such a supposition ; as sleep often takes place, when 

 the secreted fluid must be copiously present, and waking can be 

 protracted, when the fluid is exhausted much beyond its usual 

 measure. 7- Both states are induced by many causes, which 

 can hardly be supposed to act upon a secretion. " The sup- 

 position of waking and sleep depending upon a recruited fluid 

 is manifestly false and inconsistent ; so that this doctrine is to 

 be entirely rejected, and we must either give up the question 

 altogether, or seek for another solution. One which has been 

 offered, but which is by no means so commonly received or sup- 

 ported, is, that" 



CXXVI. A certain compression of the brain can produce a 

 state of the system resembling sleep ; but that state is, in some 

 respects, different from that of ordinary sleep : And it does not, 

 by any means, appear, that natural and ordinary sleep depends 

 upon any compression of the brain. " I say a state resembling 

 sleep, for in some respects it is considerably different. With 

 respect to the different states of excitability, we find that natural 

 sleep is distinguished by this, that it can be removed by mode- 

 rate stimuli, whereas this artificial sleep is not to be excited un- 

 less by removing the cause. At the same time I must say that 

 I cannot insist upon that argument. There are certain states 

 produced by the causes which induce natural sleep, but which 

 are to such a degree, that the individuals are hardly more ex- 

 citable than those in a state of stupor from compression. Thus, 

 in a man dead drunk, where I suppose the sleep produced by a 



