342 VEGETABLE DRUGS 



and faintness), followed by sleep, or a pleasant, dreamy state. 

 After-effects may be absent, or consist of nausea, headache, 

 coated tongne and constipation. If the dose is larger, sleep 

 comes on quickly, the pupils are contracted, the respiratory 

 movements and pulse become slow, and the skin is moist 



"With lethal doses, sleep deepens into coma, from which 

 the patient can at first be aroused ; the coma becomes pro- 

 found, the pulse feeble and rapid, the respiration stertorous, 

 slow and imperfect. The mucous membranes are cyanotic, 

 the face livid, the pupils dilate, and the surface is covered 

 with clammy sweat. Death occurs from respiratory failure, 

 occasionally preceded by convulsions. One-eighth of one 

 grain of morphine is the smallest fatal human dose recorded. 

 The action of opium upon man, as compared with that upon 

 the horse and ruminants, is characterized by its predominant 

 depressing effect upon the higher mental functions. The 

 motor centres of the brain and cord are only slightly 

 influenced. 



General Action of Opium Upon the Nervous System. — The 

 action of opium upon the nervous system may be summar- 

 ized in primary central stimulation, followed by depression 

 and paralysis. In man and the dog, the cerebral depression 

 is more prominent; in the horse, the stimulant action upon 

 the motor centres of the brain and spinal cord is more 

 marked ; while considerable depression only appears in the 

 later stage of poisoning. 



Opium illustrates the law of dissolution in the order of 

 its action, i. e., in the more highly organized functions being 

 the first to succumb; while the lower centres are the last to 

 be influenced. Stimulation of the cerebrum is exhibited by 

 exalted intellectual power in man; by motor excitement in 

 animals. This stage, comparatively short in man and dogs, 

 is succeeded by depression of the intellectual functions and, 

 to a less extent, of the cerebral motor centres. Depression 

 is exhibited by sleep and insensibility to sound, light, exter- 

 nal irritation and pain. Eelief of suffering often occurs 

 without sleep, and is due to the depressing action of the 



