954 



and BoEKE^). Nageotte') reproduces and describes spinal nerve-cells, 

 in which a collateral leaves the axon quite close to the nerve-cell. 

 This collateral terminates in a club-like swelling, which is situated 

 inside the capsule of the same nerve-cell. N. is of opinion 

 that these collaterals are due to legenerative activity in the cell, 

 with which Cajal') also agrees. Biei,schowsky ') interprets these 

 formations in another way ; he includes them among the fenestrate 

 cells and thinks that these processes have nothing to do with rege- 

 neration. Ranson*) has tried to discover an explanation of this 

 phenomenon by means of experiments. The results given by these 

 experiments have, without exception, indicated that these processes 

 with chib-like formations are not a product of regeneratixe activity 

 in the cell. I have however, been unable to find in the literature 

 any indication of the fact that 7- and }"-divisions occur in the dorsal 

 and ventral roots of the spinal nerves. As a working hypothesis for 

 my continued investigations I took the possibility (which is, in 

 itself, not at all probable) that the above-mentioned, or similar, 

 processes with club-like formations might develop into axons and, 

 in addition, the possibility that T- and }'-divisions might occur in 

 the intra- and extra-medullar course of the ventral roots as well as 

 in the dorsal roots, which would explain the post-embryonal increase 

 in the axons there which is under discussion. 



Silver impregnated dorsal and ventral roots of lumbal and sacral 

 nerves in connection with their spinal ganglia, and a small piece of 

 half the spinal cord on the same side from animals of different ages 

 within the same species, were set up in unbroken series (lOfi thick). 

 These series were well suited for stiulies of the figures of the growth 

 that might possibly occur, and for investigations made with a view 

 to answering the third possibility that had been advanced, namely 

 whether one nerve cell, the axons of which form the spinal nerves, 

 sends off more than one axon in the same direction. In investigating 

 the preparation a cross-table was used and the microscope was 



1) BoEKE, J. Studiën zur Nervenregeneration 11 Verhandel, d. K. Akad. v. Wet. 

 te Amsterdam. Deel XIX. N^. 5. 1917. 



') Nageotte, J. Recherches experimentales sur la morphologie des cellules et 

 des fibres des ganglions rachidiens Rev. Neurol. Paris. Vol. 15, p. 357. 



') Gajal S. Ramon y. Die Struktur der sensiblen Gangliën des Menschen und 

 der Tiere. Anal. Heft. Zweite Abt. Ed. 16. 1907. 



*) BiELSCHOWSKY, M. Ueber den Bau der Spinalganglien unter normalen und 

 pathologischen Verhaltnissen. J. Psych u. Neur, B. 11, 1908. Leipzig. 



'°) Ranson, S. Walter. The Structure of the Spinal Ganglia and of the Spinal 

 Nerves. J. Comp Near. Vol. 22. 1912. 



