174 STRUCTURE OF THE NERVOUS SYSTEM, BY MAX SCHULTZE. 



The majority, perhaps it may even be said all, of these cells 

 possess processes, which, however, in the fresh state can be 

 torn off with a facility proportionate to the difference in the 

 consistence of the cell substance and the investing capsule of 

 connective tissue. These processes are nerve fibres, as was 

 iirst observed by Remak in the Vertebrata,* and by Helmholtzf 

 amongst the Invertebrata. If only one be present, causing the 

 cell to look like a berry attached to its stalk, it is termed 

 unipolar ; if there are two which are often connected with the 

 opposite extremities of the cell, this is termed bipolar, and 

 when there are several, it is multipolar. That these processes 

 are nerve fibres is most clearly evident in certain bipolar gan- 

 glion cells, which are introduced in the course of those medul- 

 lated nerve fibres that may easily be obtained from the perfectly 

 fresh spinal ganglia of sharks and rays, where they were first 

 noticed by Robin and Rudolph Wagner^ in 1847 ; or from the 

 Gasserian ganglion of the same animals, where I have been able 

 to demonstrate their presence with great ease ; or from the same 

 ganglion of the osseous fishes (pike, according to Bidder) ; or 

 lastly, from the auditory nerve before its entrance into the 

 sacculi of the labyrinth .j| The cell substance is here a con- 

 tinuation of the substance of the axis cylinder ; it includes a 

 nucleus and nucleoli ; the medullary sheath usually ceases at 

 the point of transition of the fibre into the nucleated enlarge- 

 ment of the axis cylinder, and reappears at the corresponding 

 point on the opposite side ; though it occasionally invests the 

 entire cell, the cytoid enlargement of the axis cylinder in that 

 case occasioning no interruption to the medullary sheath. It 

 is obvious that such a ganglion cell is only a nucleated swelling 

 of the axis cylinder. The fibrillated structure of the latter 

 may be followed in the cell substance, although it is there in 



* Froriep's Notizen, 1837, Nos. 47, 56, 58 ; Observations Anat. et 

 Microscop, de Systematis Nervosi Structura. Berol, 1838. 



f Defabrica Systematis Nervosi Evertebratorum, Diss. inaug., 1842. 



J R. Wagner, Neurologische Untersuchungen, p. 7. 



Zur Lelire von dem Verhdltniss der Ganglionkorper zu die Nerven- 

 fasern, " On the relations of the Ganglia to the Nerve Fibres." Leipzig, 

 1 . 



Max Schultze, De Retince structura penitiori. Bonn., 1859, fig. 7. 



