THE NERVOUS SYSTEM. 371 



the transverse sectional surfaces of all the nerves in square lines, and 

 compared with them the transverse sectional area, taken with the utmost 

 possible nicety, of the white substance of the spinal cord, at the level 

 of the second cervical vertebra. 



It is quite true that there was now evident a very considerable diffe- 

 rence against the spinal cord ; but when the very great attenuation of the 

 nerve-fibres of the roots, at their entrance and in their further course in 

 the cord, was brought into account, which was not done by Volkmann, 

 the matter was entirely altered, and it became clear that the cord in the 

 male subject contained more than sufficient fibres to furnish the peripheral 

 ones, and in the female nearly sufficient, particularly when it is consi- 

 dered, moreover, that in the entire enumeration, the numbers were stated 

 rather in favor of the roots of the nerves (vid. the calculation in " Mikro- 

 skop. Anatom.," II. 1, 116). 



It appears, therefore, scarcely to admit of doubt, that the notion of a 

 termination of the peripheral nerves in the cord, has no support in mea- 

 surements such as those which, following Volkmann, I have adduced ; 

 . and that the latter, even when all due allowance is made for the uncer- 

 tainty always incidental to such an inquiry, on the contrary indicate, at 

 all events the probability, that the spinal nerves ascend to the cerebrum. 

 They give no further information, however, and it depends upon other 

 facts, whether such a central origin should be admitted or not, because 

 it is even conceivable, that the peripheral nerves may end in the cord, 

 and that the longitudinal fibres in the cord have a wholly different source. 

 Since it is scarcely probable that the tracing of the nerve-fibres through 

 the entire cord will be effected either at present or perhaps at any time, 

 it is necessary to look round for other facts, which may possibly afford 

 conclusive evidence on the subject ; and such facts do exist. In the first 

 place, let us consider the course of the roots of the nerves in the cord, 

 such as it has been described above. We found, that after they had all 

 come, more or less, into contact with the gray substance, the greater 

 number of them could be directly traced into connection with the longi- 

 tudinal fibres of the anterior, lateral, and posterior columns. From this 

 fact, together with my measurements, the passage of the greater part of 

 the peripheral nerve-fibres into the cerebrum, will appear to many to be 

 proved ; but, not to overlook anything, it may be further remarked, that 

 the radical fibres, running longitudinally in the substance of the cord, 

 may terminate in it, or after running in it may again enter the gray 

 substance higher up. The former supposition is now, it must be con- 

 fessed, but little probable, because in the first place, no one has yet 

 seen the terminations of nerve-fibres in the white substance ; and in the 

 second, because anything of the sort, for other reasons, would be very 

 surprising, nerve-fibres being nowhere known to commence in the white 

 substance ; and with respect to the latter, any re-entry of the roots of 



