HuBER, SympatJietic Nervous System. 121 



The pre-ganglionic nerve fibers with their terminal baskets 

 are the neuraxes and end-brushes of cerebro-spinal neurons 

 which leave the cord through the anterior root. The exact 

 location of the cell bodies of these neurons is not as yet known. 

 Gaskell (78) has attempted to place them in Clarke's columns of 

 the cord. It is now, however, well known that the neurons, the 

 cell bodies of which constitute Clarke's columns, are intra-me- 

 dullary neurons, the neuraxes of which form the direct cerebel- 

 lar tracts. 



I question the advisability of speaking of the pre-gangli- 

 onic fibers as sympathetic fibers, as Langley does in his arti- 

 cles. It is true they end in the sympathetic ganglia. Yet the 

 cell bodies of these neurons are undoubtedly in the cerebro- 

 spinal axis. They develop very much as do the motor neurons, 

 and are, as His (10) has shown, to be seen in the human 

 embryo before the milagen for the sympathetic ganglion can 

 be made out. They are cerebro-spinal fibers, forming a portion 

 of a link in a neuron chain, the terminal link of which is formed 

 by a sympathetic neuron. Neither can I consider the term 

 "visceral nerves" used by Gaskell and others as consistent, as 

 all of these nerves do not end in the viscera. 



Some term ex:pressing their central or cerebro-spinal ori- 

 gin, would seem to me more appropriate, and for want of a 

 better term they may be spoken of as central fibers. 



The post- ganglionic, or post-cellular fibers of Langley (82) 

 are the neuraxes of the sympathetic neurons of the ganglion, 

 a part of the sympathetic cell, and therefore not post-cellular. 

 These fibers are the sympathetic nerves, neuraxes of sympa- 

 thetic neurons, which as has previously been shown, end in in- 

 voluntary muscle, in heart muscle and in the glands. 



In Langley's writings, the statement that nicotin paralyzes 

 the ganglion cells of the sympathetic ganglia repeatedly occurs. 

 His reason for such a statement is, of course, based on the fact 

 that the effects which are produced when stimulating the cent- 

 ral (pre-ganglionic) fibers of a ganglion, can not be obtained 

 when the ganglion, in which said central fibers end, is painted 

 with a dilute solution of nicotin, but are obtained when the 



