George L. Streeter 107 



for by llic disproportionate growtli of the fibre elements over that of 

 the cellular elements, and of some of the cellular masses over that of 

 others; most of tlie cell masses persist, but some of tliem early reach a 

 point at which they remain stationary, such as the accessorius root 

 ganglia, and sometimes the first cervical. Following the increase in fibre 

 growth they become buried among the rootlets or on the accessorius trunk, 

 and thougli not seen by the naked eye they can be seen on section. Pig. 

 I'o represents a case in which the first cervical ganglion was macroscopi- 

 cally absent, but microscopically it is present as a large clump of normal 

 appearing ganglion cells within the sheath of the accessorius trunk. 



Anastomoses between the first cervical and the trunk of the accessory 

 nerve in the adult have excited much interest. Among others they have 

 been studied by Kazzander, 91, and later by Weigner, 01. A stu'dy of 

 Weigner's drawings shows that the accessory nerve of one side has no 

 ^constant relation to the accessory nerve of the other side in the same 

 individual; they bear themselves as independent structures, and his 37 

 examinations may therefore be considered as 74 individual cases. By 

 re-analyzing Weigner's cases in this manner instructive data on our 

 present subject have been obtained. They show that the relation in the 

 adult of the first cervical to the accessorius is as follows : 



19% — First cervical ganglion and dorsal root are present, and do not 

 anastomose w'ith the accessorius. 



19% — First cervical ganglion and dorsal root are macroscopically 

 absent. 



62%: — Various kinds of anastomosis between the first cervical dorsal 

 root and the accessorius. In many of these cases the ganglion is macro- 

 scopically absent. 



These anastomoses are doubtless to be explained on embryological 

 grounds. The relative position of the two structures at the beginning 

 of connective tissue formation would determine their permanent relations. 

 If they lie in contact at that time they become permanently adherent. 

 Secondaril}', when the dorsal roots become thus entangled in the acces- 

 sory trunk, as they are apt to in case of the first cervical, they are dragged 

 along out of their original position by later growth and the consequent 

 relative shifting of all of the structures in that region. Further 

 irregularities in their course may he caused by the accessory which, being 

 laid down earlier than they, would have tlie tendency to guide the imping- 

 ing dorsal rootlets out of the direct centripetal line to the neural tube, 

 and along its own trunk, either forward or backward. A diagram showing 

 some of these variations is reproduced in Plate IV. In the same diagram 

 is shown the hypothetical course of some of the other fibres of the acces- 



