Roth, Spinal Accessory Neii>f. 489 



Comparing these figures with those obtained from a count 

 of the anterior root fibers it will be seen that they account to a 

 very considerable extent for the increase of small fibers in the 

 fourth anterior root, a conclusion which may be clearly seen 

 from the following table. 



Ne 



Medullated fibers less than Meduliated fibers less than 4/i 

 4/^ in diameter in ramus communicans 



It must be remembered however, that the counts of the 

 anterior root fibers and those of the white rami fibers were made 

 upon different individuals and the results show only approximate- 

 ly the correlation which obtains. It seems that in the anterior 

 roots of all the upper cervical nerves there is a considable num- 

 ber of small fibers whose diameter is less than 4/i, but that a 

 sudden increase in the number occurs in the anterior root of the 

 fourth nerve and that this increase is fairly proportional to the 

 number of fibers of a similar size in the corresponding ramus 

 communicans. Furthermore, this increase occurs in the first 

 nerve below the lowest root of the spinal accessory. 



Obsoi'ations on Cats. 



The spinal accessory of the cat, according to Bischoff's 

 observations, descends to the level of the sixth cervical nerve. 

 Concerning the occurrence of white rami fibers in this animal 

 the anatomical data are rather scanty, notwithstanding its exten- 

 sive employment in physiological experimentation. 



Langley. it is true, paid some attention to this side of the 

 problem, but apparently confined his attention mainly to those 

 rami communicantes which without microscopical examination 

 could be recognized as composed largely of medullated fibers. 

 He says "in the Cat and Dog. the uppermost obvious white 

 ramus is that for the Ilnd thoracic; but with a little trouble one, 

 two, or three fine white strands can be seen stretching from the 

 1st thoracic nerve to the ganglion stellatum. When these are 



