168 REPORT— 18/0. 



first extracted, putting her finger to it, and afterwards rearranging her 

 position for the second removal. To the looker on it seemed in fact as 

 though no change in her life had occurred, yet she affirmed that she was 

 sensible of no pain whatever ; and several other less striking hut hardly less 

 singular examples came before me. We may then, I think, faiiiy assume 

 that in course of time wo shall discover manageable and certain auffisthetic 

 substances which will paralyze sensation only, leaving the muscular power 

 unaltered and the mental httle disturbed ; and we gather from this either that 

 in the cerebral hemisphere there is some distinct and simple centre of 

 common sensation which may be acted upon by certain agents without 

 involving all the cerebral mass, or that the peripheral nervous matter may be 

 influenced without involving the other portions of the nervous system. 

 On the whole, I incline to the view that the action of those agents which 

 destroy pain before they remove consciousness is primarily on the peripheral 

 system ; for we know, from the process of local anajsthesia, that it is easy 

 to destroy sensation at the extremities without destroying or even interfering 

 with consciousness, while those who have inhaled the vapours which destroy 

 common sensation before interfering with the mental condition, invariably 

 describe the experience of a numbness and insensibility in the extreme parts, 

 of the body. 



That which we medical men most require is an agent that shall ho easily 

 applied, and shall admit of being so applied generally as to induce 

 insensibility to pain with or without destruction of consciousness, as the case 

 before us may demand. There are many minor surgical operations for which 

 consciousness need not be destroyed, although pain ought to be ; there are 

 other operations in which the consciousness of the person operated upon is of 

 great service to the operator ; and there is a third class of cases in which it is 

 essential to suspend both sensation and consciousness. 



Now those agents which first destroy common sensation can always be 

 pushed to the extent of destroying consciousness, so that if we could get a 

 perfect agent of the kind we should have the full requii-emeuts in our hand. 

 Up to the present moment wo have been content with two classes of agents, 

 one which destroys consciousness and sensation at the same time, the other 

 which locally destroys sensation, and has no influence on the consciousness. 

 I look hopefully for a method in which, by means of a single agent, we 

 shall be able at will to suspend common sensation alone, or to exalt the 

 process into suspension of consciousness. When this object is attained, 

 with safety and facUity, the science of ansesthesia may be considered as 

 perfected. 



Modification of action from physical constitution and construction. — The 

 present series of researches have been sijccially interesting as showing more 

 clearly in detail the influeuce of physical constitution and construction of 

 different substances in relation to physiological action. We take, for example, 

 the base ethyl, C., H., and trace out physiological action through its many modi- 

 fications of compounds. We begin with the hydride of etkyl, C^ H^ H, and 

 find it an insoluble gas which will produce insensibility if it be made to 

 exclude air from the lungs, but which is, in other respects, negative in action. 

 We pass to the hydrated oxide of etliyl, C., H,. (alcohol), and find a fluid 

 very soluble in blood, readily ditfusible through the body, and producing, when 

 given, in sufficient quantity, a prolonged narcotism,, with suspension first of 

 common sensation and afterwards of consciousness. . We turn to ethjd-ether, 

 C, H,„ 0, and discover a volatile fluid, soluble to a certain extent in the blood, 

 capable of being absorbed by the lungs, and having the power of producing 



