724 THE CEREBELLUM 



been suggested that the constant activity of the muscles and other organs during 

 the waking hours gives rise to waste products which accumulate in the system, 

 because they cannot be gotten rid of as rapidly as they are produced. In the course 

 of time, these substances cause a nervous depression which eventually culminates 

 in sleep. While this theory also lacks experimental confirmation, it has certain 

 points in its favor. Thus, it is a well-known fact that the activity of muscle is 

 associated with the production of fatigue substances, such as carbon dioxid, sar- 

 colactic acid and monopotassium phosphate. The accumulation of these sub- 

 stances in muscle finally causes the latter to lose its irritability. Furthermore, if 

 the serum of a fatigued animal is injected into the circulatory channels of a normal 

 animal, the latter will show all the phenomena of fatigue. 



Some physiologists, among them Pieron, have gone a step farther and have stated 

 that these fatigue substances are augmented by a special toxin which might be 

 designated as a hypnotoxin. It is this agent which is assumed to produce the 

 histological changes in the cells of the brain after forced deprivation of sleep. Its 

 presence has been established by injecting the blood serum or cerebrospinal fluid 

 of such animals into the circulatory channels of normal animals. The latter then 

 showed a condition simulating sleep as well as structural changes in the cerebral 

 cortex. 



Pfliiger explains sleep by assuming that the cells of the brain are quite unable 

 to replace their store in intramolecular oxygen as rapidly as it is used up and hence, 

 their irritability must decrease gradually with the length of the period of activity. 

 This idea, however, that oxygen is stored in the cells as a product of a distinct 

 synthesis is not commonly accepted to-day. The foregoing brief discussion must 

 show that this subject is still in a very indefinite form, so that it might seem advisa- 

 ble to adhere for the present to the chemical theory and to consider the changes in 

 the pressure, flow and distribution of the blood as secondary phenomena. 



Hypnotic Sleep. — This condition is by no means identical with 

 sleep. It is brought about by producing the picture of hypnosis by 

 suggestion, a process which may be greatly facilitated by fixing the 

 attention of the subject upon a constant visual, auditory or tactile 

 stimulus, such as a glistening object, a monotonous sound, or slight 

 stroking of the skin. Facilitation of this process is effected in time by 

 repeated hypnoses until eventually a condition of autohypnosis may be 

 induced, ^.e., an ability on the part of a person to self -induce this state 

 (Cardanus, 1553). 



Contrary to sleep, the hypnotized person exhibits a decided blanch- 

 ing of his features, a muscular relaxation, a drooping of his eyelids, 

 slow and deep respirations and a peculiar change in his conscious- 

 ness which is characterized by a decided vulnerability to suggestions. 

 The vascular changes are betrayed by a decrease in the volume of 

 the arms and legs, when determined by means of the phlethysmograph. 

 Deep hypnosis, moreover, insures a loss of voluntary control of the 

 muscles and certain sensory disturbances, such as amnesia, analgesia 

 and anesthesia for touch and temperature. Curiously enough, this 

 loss of the self-regulation of muscular movements does not include the 

 control of the * voluntary muscles through suggestion. Thus, it is 

 possible to force a hypnotized person to assume different positions or 

 to inhibit the action of his muscles, so that he cannot extricate himself 

 from the most awkward idiomuscular situations. In fact, his muscles 

 may be tonically set, so that the body becomes perfectly rigid and may 



