OF THE AXIS CYLINDER. 177 



carefully prepared and mounted in glycerine, or in 

 strong syrup. The fact of the existence of such 

 fibres is of great importance with reference to the 

 question of the mode of termination and action of 

 nerve fibres, and must influence much the conclusion 

 we adopt concerning the essential structure of a 

 nervous apparatus. This part of the question has 

 been discussed in papers published in the " Medical 

 Times and Gazette," January and February, 1867 ; 

 see also, "Archives of Medicine," 1862-4; "Croonian 

 Lecture," 1865. 



236. Of the axis cylinder. What appears as the 

 single core or " axis cylinder" of a nerve fibre in the 

 nerve trunk is formed by the coalescence of very nu- 

 merous fine fibres, each coming from a different central 

 nerve cell. In following a single dark-bordered or 

 other nerve fibre towards centre or periphery, we 

 find that it divides and subdivides into a great number 

 of fibres which pursue different and often opposite 

 directions, one passing towards the centre, and the 

 other to the periphery. And these are implanted in 

 different parts of the nerve centre or peripheral organ 

 at considerable distances from one another. 



237. Advantages of the subdivision and interlace- 

 ment of nerve fibres. If, therefore, one branch of a 

 nerve fibre be destroyed by injury, accident, or disease, 

 there ought to be neither complete paralysis nor com- 

 pleteloss of sensation even of the smallest portion of the 

 body, but, on the contrary, a very slight effect should 

 be produced upon parts situated perhaps at some 

 distance from one another. Experience and ob- 

 servation have proved such to be the fact. By the 

 very free crossing and interlacing and the frequent 

 change in the course of nerve fibres in all nerve 

 centres, very serious damage to any one organ or 

 part of an organ by local disease or injury, is effec- 

 tually provided against. Were all our faculties 

 exactly localised and the great nerve organs com- 



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