liv Journal of Comparative Neurology. 



Cortical Nerve Termini.' 



Dr. Berkley controverts the belief, widely current among students 

 of Golgi preparations, that the mere interlacing of dendritic processes 

 of nerve fibers is sufficient to ensure nervous conduction by contiguity. 

 Reargues that the finest ramifications of these processes, as well as the 

 cell bodies, are enclosed in an insulating membrane and that the ter- 

 minal bulbs of the gemulae, or thorns, constitute the only avenue of 

 approach not thus protected. He figures collaterals from the psychical 

 cells which, winding among the dendrites, seldom show any definite 

 endings until the mid-portion of the layer of small pyramidal cells is 

 reached. There they split up into a number of very fine branches, 

 and eventually give off at frequent intervals exceedingly short collat- 

 erals, which ordinarily come off from the parent stem only on the side 

 of the nearest dendritic processes. These terminate in little bulbs 

 which are closely adjusted against the bulbous lips of the gemmules 

 of the dendritic process and it is between these terminal bulbs that the 

 discharge passes from one nerve unit to another, either by continuity 

 or contiguity, probably the lattep. The transmission of impressions 

 from external sources to the central cell and from local cell to local 

 cell is not accomplished by a diffusion of the excitation through the 

 whole cortex, nor diffusely through the neuropilem ; but at single 

 points, perfectly definite in their distribution, these points being situ- 

 ated only at the extremities of the nerve fiber twigs, viz. the bulbous 

 endings. c. j. h, 



YariatioiiKS in the Brachial and Lunibro-Sacral Plexas.^ 



Variations in the position of the pelvic girdle in vertebrates have 

 frequently been described In one of the best known instances, Nec- 

 turus, Mr. Waite has undertaken the investigation of the lumbro-sacral 

 plexus to determine whether the nerves composing it exhibit variations 

 which can be correlated with those of the venebrje. Thirty dissec- 

 tions were made and the variations of the nerves are shown to follow 

 approximately but not exactly those of the vertebrae. Comparison 

 with the brachial plexus shows that in case of displacement caudad 



' Henry J "Berkley. The Intra-cerebral Nerve-fiber Terminal Apparatus, 

 and Modes of Transmission of Nervous Impulses. The Johns Hopkins Hospital 

 Reports, Vol. VI, 1897. 



"^ F. C. W.\ITE. Variations in the Brachial and Lumbro-Sacral Plexi of 

 Necturus maculosus Rafinesque. Bull. Alus, Comp, Zoology, Harvard College, 

 XXXI, 4, Nov., 1897. 



