282 INORGANIC AGENTS 



the lower centres (medulla) are the last to be affected. The 

 acsesthetics resemble other narcotics in producing a primary 

 condition of stimulation of the nervous system, which is 

 followed by depression. In the first stage of anaesthesia 

 there is often struggling and excitement. This is partly due 

 to the physiological action of the drug and partly to fright. 

 In this stage the functions of the brain are stimulated and 

 then depressed. The higher functions are the first to be 

 excited, and the effect produced is very similar to that of 

 beginning alcoholic intoxication. The lower motor functions 

 are next stimulated, inducing struggling and motor excite- 

 ment. In the first stage of etherization, the local irritant 

 action of the vapor causes choking and coughing, and also 

 induces struggling. The respiratory and cardiac centres 

 are temporarily stimulated, the pulse and respiratory move- 

 ments are increased in force and frequency, and blood 

 tension is raised. The smaller animals may vomit during 

 the first stage of anaesthesia. A sub-division of the first 

 stage, sometimes described as the anodyne stage, occurs 

 when sensation is lost, before consciousness and voluntary 

 motion. Short operations, as extraction of teeth, have been 

 done by men upon themselves in the anodyne stage of anaes- 

 thesia, without pain. The anaesthetic stage is that condition 

 characterized by absence of consciousness, sensation, motion, 

 and partial loss of reflex action, and is that state suitable 

 for operations. The stimulating action of the anaesthetic 

 has ceased and there is now depression of the cerebral 

 functions, the motor and sensory tract of the cord, and, to a 

 partial extent, the reflex centres. The muscles are com- 

 pletely relaxed, and the patient lies absolutely motionless. 

 The conjunctivae fail to respond to irritation, i.e., winking is 

 not produced when the conjunctival membrane is lightly 

 touched with the finger. Occasionally the muscl+^s are seen 

 to be rigid and twitching during this stage of etherization, 

 although sensation and consciousness are absent. The 

 respiration and pulse should not be particularly altered 

 during the anaesthetic stage, unless danger threatens. In 



