THE NERVOUS SYSTEM. 405 



[The nerve-cells are simple cells, as which they were under* 

 stood even by Schwann; this is clearly and manifestly shown 

 by their form, their chemical composition, and their develop- 

 ment. "When Bidder, more lately (1. c), relying upon the fact 

 that the nerve-cells in many situations are in connection at 

 each end with dark-bordered nerve-fibres, propounds the 

 opinion that they are membraneless masses, imbedded in 

 dilatations of the nerve-tubes, he has overlooked those cells 

 from which no fibres are given off, which possess exactly the 

 same membrane as those with processes ; and has not considered 

 that there also exist nerve-cells with a single, and others with 

 numerous processes, as applied to which, his view would be 

 altogether unnatural ; and lastly, that the development of 

 these bodies indicates that the nerve-cell is formed, in iotu, 

 whether it possess processes or not, from a simple cell. It 

 has not vet been determined whether the nerve-cells of the 

 large central organs have membranes or not; Stannius was 

 unable to detect them in the Lamprey, and R. Wagner says 

 the same of the nerve-corpuscles of the electric lobes of the 

 Ray. I think I have seen a membrane in the large, many- 

 rayed corpuscles in the spinal-cord and cerebellum of man, 

 and occasionallv, also, in others, but I freelv acknowledge that 

 no membrane can be detected in all the smaller cells, nor in 

 the processes of the central cells in general. This does not, 

 however, appear sufficient to justify the denial of the existence 

 of membranes in these instances, and I believe, that in this 

 case, as in that of the finest nerve-tubes, we must for the pre- 

 sent abstain from any definitive opinion. The processes of 

 the nerve-cells, in the brain and spinal-cord, which were first 

 noticed by Purkinje, will be more minutely described when we 

 come to speak of the central organs, and the question will 

 there be discussed as to their relation to the central fibres. 

 In the ganglia, there are no cells with branched processes, 

 instead of which we find only those with one, two, rarely three 

 or four, pale appendages, which are continuous with dark- 

 bordered tubes. The nerve-cells consist, for the most part, of 

 a coagulated, although soft protein-compound, which appears 

 to correspond very closely with that of the axis-fibres. It has 

 not been ascertained whether the membranes and nuclei differ 

 essentially from it. The fatty matter, which has also been 



