418 SPECIAL HISTOLOGY. 



to render them more transparent and their medullary contents 

 fluid. I have never, under any circumstances, seen more 

 beautiful nerve-tubes of the grey substance, than in prepa- 

 rations made with 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 ium 

 by Nachet, which allows extremely thin covering-glass to be 

 employed, and consequently the highest magnifying 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 magnifying 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. 



Whether the nerve-fibres in the cord divide, has not yet 

 been fully ascertained, yet I think that I saw such an appear- 

 ance, on one occasion, in a dark-bordered fibre, and on another in 

 an isolated axis-cylinder. 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 grey substance of the 

 cord, as at first sight appears to be the case, but that the 

 greater proportion of them are curved upwards, accompany- 

 ing the longitudinal fibres of the white substance. The 



