404 INSECT TRANSFORMATIONS. 



had ocular demonstration of the fact contended for, 

 with respect to the diminished flow of blood, in a 

 man whose brain was exposed by the accidental re- 

 moval of a part of the skull; for, whenever this man 

 fell asleep, the brain was seen to shrink and subside, 

 but the moment he awoke a tide of blood was seen 

 rushing" through the vessels and swelling the brain. 

 The same is also proved by the fact> that in madness 

 and inflammation of the brain, when the blood flows 

 rapidly, the unhappy sufferer is altogether deprived 

 of sleep, unless the current of the blood is retarded 

 by strong doses of opium, or by taking away a large 

 quantity by the lancet. It will follow, that when the 

 blood-vessels of the brain are gorged, as well as when 

 they are not sufficiently full, sleep will be equally 

 produced. Force more blood into the brain than can 

 find room to flow, and drowsiness, sleep, perhaps 

 apoplexy, will follow; diminish the quantity, so that 

 it may lack force to keep up the current, and sleep 

 will also come on. *On these principles it is that 

 thinking, by bestirring the brain and driving thither a 

 brisker current of blood, prevents sleep; while, 

 bathing the feet in warm water, eating a moderate 

 supper, or rubbing the body with a flesh-brush, by 

 drawing a superabundance of blood to the feet, to the 

 stomach, or to the skin, will cause sleep. Again, it 

 is a general law of animated nature, for rest to suc- 

 ceed fatigue, as temporary insensibility succeeds vivid 

 sensations. The pain of a burn, for example, comes 

 and goes alternately; and by holding out the 'arm 

 from the body, the feeling of fatigue and pain soon 

 become so insupportable, that rest cannot be dis- 

 pensed with. Sleep, then, seems to be a general 

 consequence of this rest after fatigue. 



With regard to insects, it is evident that many of 

 the above facts will not at all apply; for as insects 

 have neither a heart nor a brain, their sleep cannot 



