April 4, 1913] 



SCIENCE 



525 



to boil vigorously in all but the mildest 

 winter weather. When this was supplemented 

 by a crescent-shaped pan on the " radiator " 

 (also inside the casing) the evaporation 

 reached twenty-five or more gallons a day — 

 this in a house of perhaps 20,000 cubic feet 

 capacity. 



A number of observations of the relative 

 humidity were made with a sling psychrom- 

 eter in both mild and severe weather. The ef- 

 fect of this considerable evaporation was to 

 raise the humidity perhaps 15 per cent, above 

 the 25 per cent, or 30 per cent, which is its 

 winter value in most houses in this climate. 

 When the value exceeded 40 per cent., how- 

 ever, very annoying condensation effects were 

 noticeable; even the double windows were 

 drenched with water, while, with zero 

 weather outside, the baseboards and furniture 

 of bedrooms which had been cold during the 

 night were wet. At 50 per cent, the conden- 

 sation became unbearable, even the walls — al- 

 though built with double air space — ^being 

 wet. With the humidity at 40 per cent., how- 

 ever — and it seldom exceeded this value with 

 the above mentioned evaporation — ^no bad ef- 

 fects were noticeable, while it has certainly 

 added very materially to the comfort of in- 

 door living and possibly contributed in secur- 

 ing immunity from colds. 



In conclusion it seems to the writer that 

 considerable effort is required to raise the hu- 

 midity even a few per cent., but that this ef- 

 fort is nevertheless well worth while; also that 

 40 per cent, is as high a humidity as can be 

 obtained in this climate in winter without 

 annoying condensation effects, even in a 

 house with double walls and double windows, 

 while '70 per cent, would mean the atmosphere 

 of a steam laundry. 



L. R. Ingersoll 



Mamson, Wis. 



SCIENTIFIC BOOKS 

 Le probleme physiologique du Sommeil. By 



Henri Pieron. Paris, Masson et Cie. 1913. 



Pp. XV + 520, six figures in text. 



This volume makes a notable contribution 

 to the large literature bearing upon the nature 



and cause of sleep. That the subject is 

 treated in a comprehensive manner is indi- 

 cated by the headings of the six parts into 

 which the book is divided, namely, the biology 

 of sleep, under which is included a discussion 

 of related conditions in plants and animals; 

 the physiological phenomena characteristic of 

 sleep, the treatment here being limited to the 

 characteristic sleep in man and the mam- 

 malia; states analogous to sleep, including 

 such conditions as coma, narcosis, the action 

 of hypnotics, hypnotic and electrical sleep and 

 hibernation; experimental observations upon 

 the factors of sleep; theories of sleep, and 

 lastly a summary of the present state of the 

 problem together with an outline of his own 

 views upon the subject. The bibliographical 

 and critical part of the book seems to be com- 

 plete and well done. The author quotes a 

 very extensive literature, and, so far as the 

 reviewer can determine from his own knowl- 

 edge of the subject, the material referred to 

 has been treated with great fairness to the 

 authors concerned. In fact the impartiality 

 and completeness shown in the presentation 

 of the numerous facts and theories ought to 

 make the book an especially valuable source 

 of information for all who are interested in 

 the subject. 



Outside this feature interest attaches chiefiy 

 to the experimental contributions made by the 

 author and to the theory which he is led to 

 adopt. His own work, done in collaboration 

 with Legendre, consisted mainly of a study of 

 the toxines produced in dogs kept from sleep 

 during periods varying from 30 to 500 hours. 

 In these animals he obtained evidence of the 

 production of a hypnotoxine which he was 

 able to detect in the blood, brain and cerebro- 

 spinal liquid. Incomplete efforts made to 

 isolate this body indicated that it is not 

 dialysable, that it is destroyed by heating to 

 65° 0. and that it is precipitable by alcohol 

 and can be redissolved in water. In the ani- 

 mals subjected to insomnia histological exam- 

 ination demonstrated that there was a distinct 

 degenerative change in the cortex of the pre- 

 frontal region. The cells were diminished in 



