RELATIONS OF ABNORMAL PSYCHOLOGY 741 



Burgerstein, Laser, Thorndike, Binet). The memory undergoes 

 a change, as we saw from the illustration cited by Ribot; acquisi- 

 tion becomes more difficult (Ebbinghaus, Finzi, Schneider); the 

 power of recollection, the certainty and the correctness of response, 

 decrease (Ranschburg), and certain classes of memories disappear 

 entirely as I have several times shown. The disturbance even 

 extends to perception (Grote, Marine, Griesbach, Leuba). All of 

 these phenomena are in striking contrast with those that occur 

 in repose. This opposition between the mind in the state of rest 

 and in the state of fatigue, is of prime importance for pathological 

 psychology. 



Similar phenomena are to be observed in the various forms of 

 intoxication; here, too, is to be seen an interesting opposition be- 

 tween the mental state of the intoxicated and of the non-intoxi- 

 cated individual. Numerous investigations, such as those upon 

 haschish by Moreau de Tours, those upon alcohol by Richet, and 

 many others, have established phenomena which are analogous 

 to the phenomena of fatigue. But I wish to direct your attention 

 to a class of investigations which has reached a high degree of de- 

 velopment in France those of sleep, or rather of sleeps, for there 

 are many states to which this general name may be applied. 



Sleep is a type of oscillation which is particularly deserving of 

 notice in this connection, because it is a wholly relative condition; 

 its phenomena can be determined only in relation to the waking 

 state. An essential characteristic of sleep is the fact that it is 

 attended by a lesser activity of the vital functions. It is not enough 

 to say that sleep is a state in which the temperature of the body 

 averages 36, the pulmonary expiration is two liters, and the pulse 

 is 54. One must add that these phenomena occur in an organism 

 which is capable when in another condition, of having a tempera- 

 ture of 37, a respiration of nine liters, and a pulse of 70. It may 

 be said that the organism is unable to keep up its more active form 

 of existence continuously, and that it practices economy during 

 a part of its life. Nor is the oscillation solely physiological; it is 

 mental as well. Dreams are the thoughts of the sleeping man. 1 

 need not remind you of all the investigations of dreams which 

 have been made from the time of Hervey de Saint-Denis and of 

 Charma, down to the recent publication of Sante de Sanctis. Let 

 me mention, however, that dreams are attended by a mental agita- 

 tion which manifests itself in hallucinations, and in a ready asso- 

 ciation of images which arrange themselves into tableaux with 

 interminable kaleidoscopic changes. Sense-impressions of slight 

 intensity give rise to complex dreams of similar modality (Maury, 

 Sergueyeff, Mourly-Vold). These dreams are characterized by ex- 



