THE NERVOUS SYSTEM. 



In order to properly, or even approximately, understand the tre- 

 mendous influence which the nervous system exercises over all 

 the other systems of the animal body in the regulation and main- 

 tenance of their varied functions, it is necessary to explain roughly 

 the methods by which this marvelous combination of cause and 

 effect is brought about; it is no uncommon thing for medical men 

 and veterinarians when asked to account for certain morbid con- 

 ditions, to attempt to disguise their own ignorance of the real 

 cause by attributing the same to the mysterious influence of the 

 nervous system, a procedure which doubtless serves to mystify 

 the enquirer and may even leave the impression that the profes- 

 sional man is a singularly learned individual; it does not, however, 

 make the matter any clearer, and therefore as passing reference 

 has, here and there, through this book been made to the influence 

 of the nerves or the nervous system in the production of certain 

 morbid conditions, we desire as far as it is possible to clear up such 

 vao-ue generalities by a simple explanation of how these effects 

 are brought about, and that before the special diseases affecting 

 the different parts of the nervous system are considered. First 

 then, of what does the nervous system consist? It may perhaps 

 render the explanation more easy of comprehension, if we liken 

 it to a large number of telegraphic oflices, all of which are 

 located under one roof and more or less intimately connected 

 too-ether.; these are represented by the brain and spinal cord; and 

 each of the respecti\-e offices is represented by what is commonly 

 known as a nerve centre; each of the before-mentioned offices has 

 a wire which conveys messages to it, and a wire that conveys 

 messao-es from it; these wires are represented by what are known 

 as nerves; for instance, an external impression is made upon some 

 part of the skin, the nerve which receives such an impression 

 conveys the message like a telegraph wire to the office or nerve 

 centre in the spinal cord, and from thence it is conveyed by the 



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