104 



there is little or no evidence of circulatory alteration. 

 Long ago Hammond described notable respiratory dis- 

 turbances in dreams while describing the pulse as being 

 unaffected, except in regard to slight* irregularity ascrib- 

 ablo to the respiratory alterations. In addition to the 

 circulation and respiration the disturbances of troubled 

 sleep may extend, in varying degree, over other systems, 

 somatic and visceral, as evidenced by sweating, tremors, 

 vomiting after awaking, etc. It is obvious that such dis- 

 turbances acting on vaj ious functions in different ways 

 may be responsible for important effects in some conditions 

 of disease. 



A notable feature (remarked long ago by Hughlings 

 Jackson) is the absence (apart from somnambulism) of large 

 movements of the limbs, etc., even during dreams of 

 vigorous exertion, while movements of fingers, lips, etc., 

 may occur, contraction of distal muscles being practicable 

 while proximal ones fail. It would seem that impulses 

 from the cerebral cortex can sometimes reach the medullary 

 centres (cardiac, respiratory, vasomotor, sweat, etc.) 

 while failing to activate the large muscles of the limbs 

 even during dreams with sti'ong emotional content. 



The Dreaming State in the Dog. 

 The phenomena observed in the human subject are 

 evidently paralleled by what is recognizable in the healthy 

 dog during dreams of hunting, etc., with the familiar move- 

 ments of toes and paws, tail and ears, biting action, series 

 of subdued barks, etc. The heart is often rapid and irregu- 

 lar with inhibitory pauses, bouts of acceleration, etc., while 

 a violent cardiac impulse may be perceived ; respiration is 

 frequently hurried and irregular, with gasps, etc. The 

 knee-jerk may be increased — as Lombard noted in man 

 during a dream of active movement. It has not been 

 found practicable to get actual measurements of blood 

 pressure that are satisfactory, for disappearance of the 

 changes present in the dreaming state is very quick 

 when the animal awakes. But the finger on an artery 

 has sometimes given unequivocal evidence of a rise of 

 blood pressure. 



Some Characters of the Nervous Disturbances. 

 The extent and intensity of the functional disturbances 

 which may be set up during troubled sleep and the 

 dreaming state are remarkable, though quite intelligible 

 in view of the diminution or suspension of the control 

 normally exercised in the waking state by higher neural 

 mechanisms, which come to be more or less completelj' in 

 abeyance during sleep ; released from such control the lower 

 mechanisms are apt to give exaggerated responses to 

 stimuli which would have comparatively little effect in the 

 daytime. Thus afferent imj)ulses (somatic or visceral) 



