1158 
respiratory oscillations in the plethysmogram. The coma-patients I 
examined did not respond to sensory stimuli, neither in the plethys- 
mogram nor in the psychogalvanic curve (see fig. 5) 
Psychogalvanom. 
Respiration. 
Pulse. 
In sleep the reaction is different. In a light sleep the pulse still 
responds when the psychogalvanic reaction has ceased (see fig. 6). 
Respiration, 
Psychogalv. 
Pulse. 
In a profound sleep, however, as in coma, no reaction manifests 
itself (see fig. 7). 
This investigation establishes, therefore, the relationship existing 
between preoccupation and stupor on the one hand, and between 
sleep and coma on the other. 
