THE NERVOUS SYSTEM. 369 



chromic acid, and I think that of all known means this is the best for 

 their study. In employing pressure, however, great care is requisite. 

 I make use of a compressor iiun by Nachet, which allows extremely thin 

 covering-glass to be employed, and consequently the highest magnifyino- 

 powers ; if I wish to apply more considerable pressure for the study of the 

 coarser conditions, the common apparatus suffices, with which, however, 

 with a shorter focal distance of the microscope, only lower powers can 

 be employed. I have had entire transverse sections of the spinal cord 

 before me, in which it might be said, that no part was disturbed from its 

 relative position, and yet, which admitted of the application of a mag- 

 nifying power of 350 diam. I would, moreover, remark, that the most 

 favorable place in the cord for the first investigation, is the lumbar 

 enlargement. In this situation the cord is not so thick, but that entire 

 sections of it may be obtained, besides which the white substance, which 

 is only an impediment, is thin, and the roots and commissures large and 

 more readily traced. 



AVhether the nerve-fibres in the cord divide, has not yet been fully 

 ascertained, yet I think that I saw such an appearance, on one occa- 

 sion, in a dark-bordered fibre, and on another in an isolated axis-cylin- 

 der. In any case such divisions cannot be frequent, otherwise I must 

 have noticed them more often, having examined innumerable nerve-fibres 

 and axis-cylinders, expressly with reference to this point. Anastomoses 

 between the processes of branched nerve-fibres, which Schroder van der 

 Kolk thinks he has seen, I must, from my experience so far, doubt, but 

 I am not able to deny their possible occurrence. 



§ 113. Probable course of the Fibres in the Cord. — We have found 

 that the motor and sensitive roots do not terminate at the point where 

 they are implanted into the gray substance of the cord, as at first sight 

 appears to be the case, but that the greater proportion of them are curved 

 upwards, accompanying the longitudinal fibres of the white substance. 

 The important question now arises, viz. : to ascertain what becomes of 

 these fibres, whether, after running a shorter or Jonger distance, they 

 terminate in the cord, or whether they all ascend to the brain. It is 

 well known, that until recently, most observers have been of the latter 

 opinion, which was founded less upon direct observation than on the 

 ground of probability, until Volkmann, in his deservedly celebrated 

 article, " Physiology of the Nerves," shook it to its foundations, carry- 

 ing the greater number of physiologists with him. I also was among 

 these, until I had myself investigated the conditions, for there could be 

 no doubt that Volkmann's theo-'y connected, in the most harmonious 

 way, the anatomical facts and the results of physiology as at that time 

 exhibited. When I now, notwithstanding this, abandon Volkmann's 



theory of the termination of the spinal nerves in the cord, I am induced 



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