ANAESTHESIA. 47 



system. The nasal, buccal, auricular, and genital mucous membranes 

 exhibit reflexes long after other parts have become insensitive. Even 

 when ansesthesia appears complete, struggling often results immediately 

 the knife touches the diseased region. This is due to certain diseased 

 tissues retaining a morbid sensibility even after neighbouring healthy 

 tissues have entirely lost sensation. Inflamed parts especially retain 

 their sensibility long after healthy tissues. Once established, anaes- 

 thesia can be maintained by very small doses of the agent employed ; 

 larger amounts are danger-ous, as being liable to induce the third stage 

 of anaesthesia, viz. collapse or intoxication. This is characterised by 

 progressive retardation of respiration and circulation, and by sudden 

 dilatation of the pupil. Respiratory movements become superficial and 

 cease for comparatively long periods; the heart's action diminishes, 

 the pulse is small, soft, and irregular. Finally the medulla becomes 

 intoxicated, respiration is arrested, the heart ceases to beat, and death 

 occurs by respiratory syncope. ^ 



The phenomena of anaesthesia yary according to whether ether, 

 chloroform, or another anaesthetic is'employeidi -With ether the period 

 of excitement is longer and more pronounced than with chloroform. 

 With certain fixed anaesthetics the phase of excitement is suppressed 

 or little marked. Although the exact action of chloral is still open to 

 discussion, it is known to produce immediate and profound anaesthesia 

 without preliminar)- disturbance when administered intra-venously. On 

 the other hand, salts of morphine sometimes produce lively excitement 

 prolonged for some hours. The difference, however, interests physiolo- 

 . gists more than practitioners. The chief point for the latter is the 

 degree of toxicity of these agents, i. c. the danger attending their use. 

 No general anassthetic is without danger, and even in veterinary surgery, 

 where their employment is limited, every practitioner has probably had 

 a fatal case. 



AncEdlicsia in the Horse. 



Chloroform probably produces the most rapid and complete anaes- 

 thesia in the horse. It is not so dangerous for solipeds as has been 

 suggested.. The writer, whose experience extends to over four hundred 

 cases, has only seen two fatal results, which occurred after deep surgical 

 anaesthesia had been maintained, in one case for over two hours, a^ 

 in the other over three. Needless to say, recovery of consciousness 

 is slow after prolonged operations, and the animals may not rise for 

 half an hour to an hour after their termination, but given reasonable 

 care in administration chloroform fulfils all requirements. 





