WHAT DXEAMS ARE MADE OF. 27$ 



ously, save for an interval of five hours; and beginning to sleep 

 on March 9 at 10 A.M., he slept until the i5th at four o'clock in the 

 afternoon. Nothing remarkably abnormal or in the least sufficient 

 to explain the anomalies of this patient's existence was revealed by 

 an examination of the brain after death, which occurred at the close 

 of the year last mentioned. Here the tendency to sleep was a 

 matter of abnormal action of some mysterious kind. There was no 

 power, as in Colonel Townshend's case, to induce the phenomena at 

 will ; but the nature of the conditions inducing or favouring the 

 peculiarities remains in either case an insoluble mystery. 



The occurrence of such anomalous cases receives no direct ex- 

 planation from any of the conditions which are known to be charac- 

 teristic of normal sleep. The resemblance of the insensibility 

 produced by congestions and fulness of blood in the brain to natural 

 sleep long ago suggested that, in some such mechanical cause as a 

 normally recurring fulness of the vessels of the organ of mind, a cause 

 of sleep might be found. But the analogy between induced insensi- 

 bility and sleep is not complete or correct. There exist many and 

 wide differences between the production of coma or stupor and that 

 of a normal insensibility to outer affairs, which sooner or later resolves 

 itself into wakefulness ; and the conditions observed in the sleeping 

 brain were, moreover, widely at variance with the known symptoms 

 of abnormal insensibility. In 1821 a Dr. Pierquin, of Montpelier, 

 placed on record the observation that in a patient, part of whose 

 brain was exposed through disease, there was no movement of the 

 organ of mind in ordinary undisturbed and dreamless sleep. When, 

 on the contrary, the sleep was disturbed by dreams, the brain sub- 

 stance was elevated in proportion to the vivid nature of the dream. 

 In her waking state, this patient exhibited the same appearances ; 

 there was marked activity of the brain when she was engaged in 

 lively or excited conversation. Experiment has, however, proved to 

 us that without doubt the brain-substance receives less blood during 

 sleep than in the waking state, which latter is accompanied by an 

 increased flow of blood to the organ. Such a result is exactly that 

 which the general inductions of physiology might have foretold. 

 Blood passing to the brain is required and used for two purposes 

 namely, for the nutrition and physical conservation of the organ, 

 and for supplying the potential energy, to be converted into thought, 

 nerve-force, and the acts of life. During sleep, therefore, blood will 

 be demanded for the first purpose alone. The wakeful activity 

 which demands and requires the larger blood-supply is no longer 

 represented, save, indeed, under abnormal conditions. And we 

 thus arrive at a basis for constructing a theory of sleep and its causa- 

 tion, just as, at the commencement of this paper, we discovered a 

 plain justification for its occurrence as an act and part of life. 



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