748 FUNCTIONS OF THE CEREBRUM [CH. L. 



of chloroform in the inspired air should never rise over 2 per cent. ; 

 smaller percentages may be employed when once the patient is under 

 the influence of the drug. There have been several instruments 

 invented (by Waller and others) by means of which the concentration 

 of the chloroform given can be easily measured. 



But the artificial sleep of a deeply-narcotised animal is no criterion 

 of what occurs during normal sleep. The sleep of anaesthesia is a 

 pathological condition due to the action of a poison. The drug 

 reduces the chemico-vital activities of the cells, and is, in a sense, 

 dependent on an increasing condition of exhaustion, which may culmi- 

 nate in death. Natural sleep, on the other hand, is the normal mani- 

 festation of one stage in the rhythmical activity of nerve-cells, and 

 though it may be preceded by fatigue or exhaustion, it is accom- 

 panied by repair, the constructive side of metabolic activity. This 

 is true for many other organs in addition to the central nervous 

 system ; sleep is a time of repose for them also, but the amount of 

 rest varies ; the voluntary muscles, except those concerned in breath- 

 ing, will rest most, but the heart continues to beat, the urine is still 

 being secreted, the processes of digestion go on, so that for such 

 organs activity is only diminished. 



It should be recognised by the public that sleep is the period of 

 anabolism, repair and growth, and a large allowance is therefore 

 necessary in growing children. The mistaken Spartan discipline of 

 certain parents and schoolmasters in insisting upon a short period of 

 repose often does incalculable harm both mental and physical to 

 those under their charge. When in the children of the poorer classes, 

 early rising for the purpose of earning a miserable pittance is com- 

 bined with late hours of retiring to rest, and with the discomforts of 

 crowded bedrooms, and crowded beds which render real rest impos- 

 sible, the damage done is greater still, and is one cause of physical 

 deterioration. Many children judged to be "defective" are really 

 only suffering from want of sleep. 



Loss of sleep is more damaging than starvation. Dogs will recover after being 

 starved for three weeks, but they die from loss of sleep in five days. The body 

 temperature falls, reflexes disappear, and post-mortem the brain is found to contain 

 capillary haemorrhages, the cord is dry and anaemic, and fatty degeneration is found 

 in most of the tissues. 



In man, loss of sleep curiously enough causes a slight rise in weight ; the body 

 temperature falls ; the excretion of nitrogen and still more so that of phosphoric acid 

 increases ; the reactions of the muscular, and later those of the nervous, system 

 diminish in intensity, except that in all cases there is an increase in acuteness of 

 vision. These experiments were made by Patrick and Gilbert on three young men, 

 who voluntarily went without sleep for ninety hours. At the end of the experiment 

 a very small extra amount of sleep beyond the normal caused complete restoration, 

 and all the symptoms, including the increase of weight, disappeared. 



The sleep produced by hypnotic suggestion differs from ordinary sleep. But 

 exact knowledge of the phenomena of this kind of sleep is at present lacking. 



