400 W. H. GASKELL. 



surrounded the straight intestine of the Crustacean-like animal 

 from which the Vertebrates arose^ we find a decided diflference 

 of structure from what occurs in the higher parts of the central 

 nervous system. Here the central grey matter is very mucli 

 subordinated to the surrounding white matter. The white 

 matter is remarkably free from any scattered nuclei in it, and 

 contains a large number of giant nerve-fibres which run 

 longitudinally. The grey matter contains but little of the 

 spongy reticulated substance^ and very few of the small 

 nerve-cells with circular nuclei as compared with the higher 

 parts of the central nervous system. 



It is significant, in connection with the meaning which I 

 ascribe to these small nerve-cells, to find that Ahlborn, after 

 criticising the view ascribed to Freud, that fibres of the 

 posterior roots are in connection with certain large cells, 

 speaks as follows (3, p. 242) : ^' Dagegen glaubeich nicht mehr 

 bezweifeln zu diirfen, dass die dorsalenNervenwurzeln wenig- 

 stens zum Theil thatsachlich ihren Ursprung in den ^ kleineren 

 Zellen ' Reissner's nehmen.^' In addition to these small nerve- 

 cells, Reissner (9) desci'ibes two groups of large ceils — (1) an 

 inner group situated bilaterally close to the central canal on 

 the dorsal side, and (2) an outer group situated near the ex- 

 tremity of the elongated band of grey matter. This latter 

 group is recognised by Ahlborn and others as corresponding 

 to anterior horn-cells. The inner group were the " Hinter- 

 zellen," supposed to be connected with the fibres of the 

 posterior roots. Ahlborn, however, can find no trace of such 

 connection, and he cannot say what their connections are; 

 all he finds on sagittal sections are (3, p. 242) " kurze, 

 starke, nach vorn (nasalwarts) gerichtete Zellfortsiitze und 

 eben solche feinere, die sich sehr schuell in rein dorso-ventraler 

 Richtung (nach oben) auflosten." 



In addition to these three kinds of cells, which are all 

 nervous, a fourth kind is found which are recognised by all 

 observers as non-nervous. These cells are described by Ahlborn 

 as lying thickly crowded near the central canal, and difiused 

 over the whole of the grey matter. He then goes on to say 



