Obkrsteiner. The Structure of the Nervous System. 8i 



1. The terminal brush ends free at the periphery ; e. g. at 

 the motor end-plate of a muscular fibre. 



2. The terminal brush enters into physiological connection 

 with the nerve cell of a second neurone, or with the nerve cells 

 of several other neurones. 



3. The terminal brush enters into physiological connection 

 with the terminal brush of another neurone, possibly with sev- 

 eral neurones. 



Although this is a matter of anatomical relations chiefly, 

 yet I have always spoken expressly of physiological connection. 

 We were a short time ago of the opinion that an unbroken fibre 

 system was necessary for the transmission o'f nervous activities. 

 The intercalation of nerve cells did not break the continuity, 

 because in them the primitive hbrillfe did not come to an end, 

 but merely suffered a change of position (M Schultze). Forel 

 (Arch. f. Psych.. 18 Bd.) and His (Abh. d. k. Sachs. Ges. d. 

 Wissensch., 13 Bd.) were the first who showed distinctly that 

 in order to render the transfer of the stimulus possible it is 

 only necessary for the nervous elements to be contiguous, to lie 

 adjacent to each other, or to intertwine. We formerly believed 

 that actual anastomosis between the processes of the function- 

 ally connected nerve cells was indispensable. The proof of 

 such gross anastomoses, however, was not possible (except in 

 certain special cases; e. g. in the spinal cord of electrical fishes 

 — Fritsch), and to trace out the finest anastomoses in the confu- 

 sion of the ultimate ramifications would be regarded impractica- 

 ble a priori. Successful silver or sublimate preparations, which 

 render the finest ramifications clearly visible, also militate against 

 the presence of anastomoses. .Again. KoUiker and Ramon y 

 Cajal observed that terminal ramifications of the nerve-felt, as 

 extremely delicate, varicose fibrils, entwine the nerve cells and 

 end on their free surface, often with fine tubercles. In a similar 

 way the fibrils of the spiral fibres twine around the sym- 

 pathetic cells (Ehrlich), as can be clearly seen after stain- 

 ing intra vivam with methyl blue. Hence, although we 

 were before obliged to assume a continuity of the elements 

 for the uninterrupted propagation of the nervous excitation, now 

 we may no longer utterly reject the view that possibly even their 

 contiguity may have the same functional significance. 



