486 Journal of Comparative Neurology and Psychology. 



consisted again of three bundles, one of which was large and 

 grey, containing only about half a dozen small medullated fibers, 

 the second small and almost entirely grey, while the third was 

 almost entirely composed of white fibers, although two small 

 groups of grey fibers occurred at its periphery. These two 

 small bundles were fused in the upper part of the ramus. The 

 first thoracic ramus consisted of five bundles, one of which was 

 exceedingly small, consisting of not more than about one dozen 

 fibers, six of which were medullated. Of the other bundles 

 two were almost entirely grey, containing each from ten to 

 twelve medullated fibers, while the other two were mainly 

 white, one entirely so, the other however containing a consid- 

 erable number of grey fibers. Finally in the second thoracic 

 ramus four bundles were present, two of which were almost 

 entirely grey, containing each only a half dozen small white 

 fibers, while the other two were entirely white. 



In connection with the second thoracic there are two bun- 

 dles which may properly be designated white rami, in connec- 

 tion with the first thoracic one, and in connection with the three 

 lower cervical none. But in each of the cervical rami and in an 

 additional bundle of the first thoracic small white fibers exist 

 which are in no wise different either in appearance or size from 

 fibers composing recognized white rami. Only by determining 

 the origin and termination of these fibers can it be definitely 

 decided that they are really white rami fibers, but if there is any- 

 thing to be concluded from their size and their similarity to the 

 fibers of the white rami, then they are undoubtedly of the same 

 nature as these latter, and they will be termed white rami fibers 

 in what follows. 



Evidence as to the nature of the fibers may be derived 

 from physiological experimentation. The observations of Naw- 

 ROCKi and Przybylski (1891) and more especially of Langley 

 (1892) certainly do not favor tlie view that the fibers in ques- 

 tion are white rami fibers, since they found that in the cat, in 

 which the conditions are very similar to those obtaining in the 

 dog, no dilatation of the pupil resulted from stimulation of the 

 anterior roots of nerves above the eighth cervical, Langley 



