362 V'EGETABLE DKUGS 



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

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

 coated tongue 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 imjDerfect. The mucous membranes are cyanotic, 

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

 Vv'ith 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 opiiim 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 on the nervous system may be summar- 

 ized as follows: 



1. On the cerebrum,. The predominant action of 

 opium on man and the dog consists in deiDression of the 

 higher brain centres with the production of nervous sedation 

 and sleep. ~ In the hind-brain depression of the perceptive 

 centres gives relief from pain. In the fore-brain depression 

 of the centres for intellect — especially of will and attention — 

 causes sleep. The middle or motor area of the brain is com- 

 monly not affected imtil paralyzed in fatal poisoning. In 

 horses and cats, however, toxic doses do stimulate the cere- 

 bral motor centres. A primary stimulant stage in the action 

 of opium on the brain of man is sometimes evident. 



In this there is a feeling of well-being and enhanced 

 m.ental powers. But the stimulation is brief and rarely uni- 

 form, imagination being increased at the expense of reason 

 and judgment. This stage is often wholly absent. In the 

 lower animals — other than dogs — the sedative and hypnotic 

 effect of opium is less certain and may be completely want- 

 ing. 



In a general way small and moderate doses cause cerS' 



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