SECT. 112.] NERVOUS SYSTEM. 225 



Whoever wishes to become acquainted with the particulars of Vol km nun's 

 statements and my refutation of them, may find them in my Microscopical 

 Anatomy. 



The more recent works of Stilling, Clarke, myself, R. Wagner, Bidder and 

 his scholars, and Schroder r. d . Kolk, upon the spinal marrow, differ in many 

 respects ; and I may notice here some of the principal points. The principal 

 difference consists in this : that Bidder and others assert, that all the fibres of 

 the roots of the spinal nerves, as well as all the fibres of the white substance, 

 are connected with the nerve-cells in the spiual marrow, whilst, according to 

 me, many nerve-fibres proceed directly from the brain towards the periphery, 

 and vice versa. Moreover, Schroder eon der Kolk and R. Wagner assert, that 

 the nerve-cells also anastomose by means of their processes, whilst it has not, 

 in my opinion, been demonstrated that these processes, which I was the first 

 to declare as a kind of nerve-fibres, have not also free terminations. 



With reference to the course of the fibres in the cord, Stilling has 

 advanced a hypothesis which holds a middle position between the one 

 defended by me and that of Volkmann. Stilling is of opinion; 1, that all 

 the fibres of the motor roots arise from the cells of the anterior horns ; 2, 

 that the majority of the fibres of the sensitive roots probably pass directly 

 into the longitudinal fibres of the posterior columns ; 3, that the remaining 

 portion of the longitudinal fibres of the white substance, accordingly, the 

 anterior and lateral columns, take their origin from the cells of the gray 

 substance ; 4, that the anterior commissure represents a connection of the 

 two anterior horns ; and, 5, that the gray substance contains no special fibres. 

 Wagm r, on his part, is inclined to hold, that first, all the- nerve-cells of the 

 cord anastomose with each other, and, secondly, that the greater part also of 

 the fibres arise from the cells, yet the special descriptions of these relations, 

 which he has given in his last work, differ very considerably from each other. 

 As far as I am concerned, it appears to me in the first place as yet impossible 

 to give an accurate exposition of the course of the fibres in the cord, and the 

 following, accordingly, may be regarded only as an outline to be filled up by 

 future researches. First of all, it appears certain, that part of the spinal 

 nerves do not arise in the cord, but in the brain ; and I am not disinclined 

 to assume, that part of the sensitive fibres of the skin and of the outermost 

 parts of the mucous membranes, as well as of the motory fibres of the 

 voluntary muscles belong to this category. Secondly, I consider it as 

 probable, that the fibres proceeding from the spinal marrow to the sympa- 

 thetic and other parts, as vessels, cutaneous muscles, bones, etc., which are 

 but remotely connected with conscious sensations and subservient to the 

 involuntary movements, in as far as they do not come from spinal ganglia, 

 arise in the spinal cord from the nerve-cells.* Thirdly and lastly, I think I 

 am warranted in affirming the existence of anastomoses of the nerve-cells, 

 although I do not assert that their processes may not also run out into free 

 extremities, and, without entering into direct connection with the nerve-fibres, 

 act upon the latter. Since, at any rate, all the elements of the nervous system 



* A part of these fibres, also a part of the sensitive fibres of the skin, and of 

 the motor elements of the voluntary muscles, may possibly take their origin 

 in the spinal marrow, which fibres then would correspond to the excito-motory 

 elements of Marshall Hall 



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