Hardesty, spinal Ganglion Cells. 45 



branches to the blood vessels, etc., proximal to the vertebral 

 column/ Such an arrangement would give two extra fibers on 

 the peripheral side of the spinal ganglion. It should be men- 

 tioned, however, that Dogiel ('97) who has made a study of 

 these cells, was unable to trace any of their processes beyond 

 the confines of the spinal ganglion. He considers them either 

 sympathetic or modifications of his spinal ganglion cell of 

 Type II. 



Finally let it be added that early in this investigation counts 

 were begun of the medullated fibers in the rami communicantes 

 with the hope of gaining some clue as to the proportional part 

 they play in forming the distal excess. It was soon found that 

 the number of fibers in the distal excess of a nerve is often 

 greater than the number of medullated fibers in its ramus and 

 since many of the fibers of the ramus are of undoubted spinal 

 origin and many of the smallest of uncertain origin, the research 

 was discarded as unprofitable in that the ramus cannot account 

 for all of the excess and in that it was impossible to determine 

 the exact proportion it does contribute. So far the conclu- 

 sions must be general, namely, that the distal excess is due to 

 several causes, though probably the greater amount of it is due 

 to medullated sympathetic fibers connected with the spinal 

 ganglion but which are not continued into the nerve roots. 



VI. The gain of cells and fibers zvitJi the gain of zveight. 



BiRGE ('82) determined that the frog while increasing from 

 1.5 grams to 1 1 1 grams gained in the ventral roots of its entire 

 spinal nerve 5 i fibers for each gram of weight gained. This 

 estimation was based upon counts of all the ventral roots of one 

 side of 6 specimens. He also counted the dorsal root fibers of 

 one side of two frogs, one weighing 23 and the other 63 grams. 

 Computations based upon the numbers he obtained give for all 

 the nerves of both sides a gain of j'] dorsal root fibers per 

 gram of weight gained. His data are not sufficient upon which 

 to base estimations of the gain of fibers on the distal side of 

 the spinal ganglion. The author ('00) dealing with the Vlth 

 spinal nerve alone of frogs varying from 5 to 79 grams, ob- 



