370 VEGETABLE DRUGS 



spiritj timidity, and nausea, lasting for several hours. The action of 

 opium on dogs differs from that on man only in degree. The dose re- 

 quired is proportionately larger. There are often more preliminary ex- 

 citement and symptoms of reflex irritation, as muscular twitching. These 

 animals do not sweat, and the pupils are not so continuously contracted 

 in poisoning. Failure of the drug to produce sleep, and the presence of 

 nausea, retching, dreams, delirium, hallucinations, occasionally observed 

 in dogs are common to man. Convulsions rarely occur in either men 

 or dogs. 



Action on Man. — In man, a small dose of .morphine (% gr.) causes 

 usually a sense of well-being, together with itching of the nose, and 

 later, of the skin generally, dryness of the mouth (occasionally there 

 may be ngusea, vomiting and faintness), followed by sleep, or a pleas- 

 ant, dreamy state. The senses are less keen, with poorer vision and 

 inhibited perception of pain or touch. After-effects may be absent, or 

 consist of nausea, dizziness, 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 profound, 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 mor- 

 phine subcutaneously is the smallest fatal human dose recorded. (Ave- 

 rage dose for man, gr. 14.) The action of opium upon man, as com- 

 pared 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 summarized as follows: 



On the Cerebrum. — The predominant action of opium on man and 

 the dog consists' in de|)ression of the higher brain centres with the pro- 

 duction of nervous sedation and sleep. In the hind-brain depression of 

 the perceptive centres gives relief from pain. In the fore-brain depres- 

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

 causes sleep. The middle or motor area of the brain is commonly not 

 affected until paralyzed in fatal poisoning. In horses and cats, how- 

 ever, toxic doses do stimulate the cerebral 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 mental powers. 

 But the stimulation is brief and rarely uniform, imagination being in- 

 creased 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 cerebral depres- 



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