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a few Ipointe in connection witb 

 tbc pb^aiolog^ of tbe Special Seneee. 



By Arthur J. Hall, B.A., M.B. Cantab., M.R.C.P., 

 Lecturer on Physiology at the Sheffield School of Medicine. 

 (Being the Presidential Address delivered before the Sheffield Micro- 

 scopical Society at the opening of the Session 1894 — 5.^ 



1HAVE selected as my subject for this evening The Special 

 Senses, in the hope that there may be something about them 

 which you may not all have heard before, and even if you 

 have, may yet bear repetition. Man is usually said to be endowed 

 with five special senses — Sight, Hearing, Taste, Smell, and Touch. 

 Let us first enquire what that means. In the two former lectures* 

 I have had the honour of giving you, I have insisted at some 

 length on the fact that a living organism such as man is really an 

 enormous colony of separate living microscopic cells, which work 

 together in different departments for the common good. Each 

 little mass of living substance or cell lives its own life ; but in 

 doing so depends on all the other cells for their assistance, and in 

 turn must do its quotum for the general welfare of the whole. And 

 as there can never be a harmonious co-operation of individuals 

 unless there is some recognised superintendent, or master, or head, 

 so in this colony we have a special group of cells to which this 

 duty is assigned — namely, the Nerve-cells, making up the brain 

 and spinal cord, or what we call the Central Nervous System. 

 These cells, which compose our Central Nervous System, alone 

 have the property of consciousness and the power of producing 

 conscious effects when stimulated in various ways. It is of the 

 highest importance that such valuable cells as these should not be 

 exposed to injury from without, just as it is important that an 

 army in battle should not lose its commander. And so we find 

 the Nerve-cells forming the brain and its accessories enclosed in a 

 hard, bony case — namely, the skull and vertebral column. But 

 this very enclosure of our only conscious cells removes them at 

 once from the very position they should hold if they are to be 

 conscious of what is going on around — namely, the surface of the 



*See this Journal, Vol. III., p. 257 j and Vol. IV., p. 225. 



