26 



NATURE 



[November 12, 1891 



what too [far in his advocacy of pure water, when he 

 says that " scientific investigation also reveals the fact 

 that, as a community is supplied with pure water, there 

 is not only a decrease in the disease and death-rate, 

 but often a most surprisingly rapid increase in thrift, 

 morality, and degree of civilization." We should be 

 glad indeed if he were correct in his statement that 

 since the introduction of an efficient health administration 

 in England, the prevalence of typhoid has been reduced 

 to such an extent that "for weeks and even months 

 not a single case now occurs in the city of London." We 

 can readily understand that our rivers must appear 

 insignificant enough to the inhabitants of a country con- 

 taining such mighty streams as the St. Lawrence, the 

 Mississippi, and the Ohio ; and although we are fully 

 alive to some of them being disgracefully fouled, we 

 certainly are somewhat startled to have our watercourses, 

 which are dear to many of us, disposed of in the following 

 sentences : — " The pollution of English streams is carried 

 to such an enormous extent that the waters of many, 

 where city sewage enters them, are actually offensive, 

 and during the summer months, owing to the stench, the 

 passenger traffic is forced to the railroads. In some of 

 these streams the whole surface of the water, for some 

 distance below sewage entrance, is in a state of commo- 

 tion, owing to the evolution of gas bubbles, and the water 

 is so foul that it cannot be used in the boilers of the 

 little steamers that ply across the rivers. Immediately 

 below the entrance of sewage no life can exist in the 

 water, on account of the presence of ferrous sulphate {sic), 

 which is a disinfectant." In dealing with the much 

 vexed subject of the apparent self-purification of streams, 

 the author shows a very just appreciation of the matter 

 when he points out that there " is no guarantee that run- 

 ning water is perfectly wholesome at any distance below 

 a point where it is certainly polluted with the contents of 

 sewers and privy-vaults, or the decomposition of vegetable 

 and animal matter. The question as to what extent must 

 impure water be diluted or oxidized to render it safe for 

 domestic purposes, cannot be answered. Mere dilution 

 of polluted water does not render inoperative the action 

 of living bacteria. . . ." We are glad to see that the 

 author points out the importance of boiling all drinking- 

 water which is open to suspicion, for it cannot be too 

 frequently reiterated that perhaps the two most eff'ective 

 measures which the private individual can take in avoid- 

 ing zymotic disease consist in boiling the water and 

 milk that are used for drinking. The largely increasing 

 consumption of ice, which in America has assumed 

 enormous proportions, is a matter which also calls for 

 very careful attention, since recent experiments have 

 shown that, although the living bacteria in ice are con- 

 siderably less numerous than in the water from which 

 the ice has been derived, still the process of freezing, 

 even if long continued, affords no sort of guarantee that 

 the dangerous forms originally present in the water shall 

 have been destroyed. Thus the bacillus of typhoid fever 

 has been found still alive in ice which had remained 

 continuously frozen for a period of 103 days. 



Percy F. Frankland, 



NO. 1 1 50, VOL. 45] 



CAUSATION OF SLEEP. 



The Intracranial Circulation and its Relation to the 

 Physiology of the Brain. By James Cappie, M.D. 

 (Edinburgh : James Thin, 1890.) 

 '"pHE factors concerned in the production of sleep have 

 J- from time to time engaged the attention of physio- 

 logists, and various theories have been advanced to 

 explain the phenomena. The author of the work now 

 before us, so far back as 1854, published a short essay on 

 " The Immediate Cause of Sleep," which he subsequently 

 expanded into a volume entitled "The Causation of 

 Sleep" (Edinburgh, 1882). In the work now under con- 

 sideration, although with a different title, the author 

 travels over much the same ground as that surveyed in 

 his previous writings on this subject, and adds to it some 

 additional chapters. 



In his successive publications Dr. Cappie accepts the 

 position usually taken up by physiologists, that the state 

 of sleep is accompanied by a diminished brain circula- 

 tion ; but he combats the view that sleep is due to a 

 diminution of the whole mass of blood within the cranial 

 cavity, and that the compensation for this diminution is 

 got by an increase in the amount of cerebro-spinal fluid 

 in the ventricular and sub-arachnoid spaces of the brain. 

 His objection to this opinion is based upon its not being 

 reconcilable with either the physics or the physiology of 

 the parts situated within the cranium. As regards the 

 physics, he adopts the view advocated by Drs. Alexander 

 Monro (secundus), Abercrombie, and Kellie, that, inas- 

 much as the brain lies within a closed cavity, which pos- 

 sesses rigid bony walls, the contents cannot be affected 

 directly by the pressure of the atmosphere, which can 

 only influence the interior of the cranium through the 

 blood-vessels, so that a force is constantly in operation 

 to maintain the amount of blood within the intracranial 

 vessels. The author believes that the effect of the 

 pressure on the blood-vessels, say of the neck and head, 

 is opposed to the movement of the blood in the veins, 

 and that the tendency of the pressure is to keep the 

 blood within the veins which ramify in the vascular mem- 

 brane enveloping the brain, called the pia mater. At 

 the same time, however, the arterial stream drives the 

 blood onwards into the capillaries and the veins, which 

 tends to dilate the latter vessels, and, in conjunction with 

 the backward pressure on the great veins, to retard the 

 flow of blood through the veins of the pia mater, and 

 consequently through the great venous sinuses of the 

 head, into the jugular veins. In this way he infers that, 

 whilst the brain itself becomes less vascular, the mass of 

 blood within the cranial cavity continues the same, but 

 its mode of distribution is altered : a less proportion i& 

 within the arteries and capillaries, whilst an increase 

 takes place in the contents of the veins of the pia mater. 

 The author acknowledges, in connection with the nutri- 

 tion of the brain, that molecular actions of a subtile kind 

 take place between the blood and blood-vessels and the 

 nervous tissues, and that these are much less active 

 during sleep than when awake. The lessened activity in 

 the nutrition of the nerve protoplasm diminishes the 

 activity of the capillary circulation. He regards, how- 

 ever, the change in i^the balance of the circulation 



