Meyer, Data of Modetn Neurology. 285 



sion of nervous impulses). His first claim is that the fine end- 

 branches of fibers are endowed with a ' protective sheath of 

 great tenuity not easily recognized by ordinary methods of 

 staining, which the sil^^er method does not show at all. It is 

 therefore more than probable that it is only at the free bulbous 

 termination of the nerve-filaments (shown by the silver method 

 only) that we have naked protoplasms, and from this uncovered 

 nervous substance the dynamic forces, generated in the cor- 

 pora of the cells, are discharged, through contiguity, on to the 

 protoplasmic substance of other cells.' This limits the func- 

 tional contact to these end-bulbs. Berkley further assumes the 

 presence of a protecting membrane around cell-bodies and den- 

 drites. The fine stems of the gemmules of the dendrites pierce 

 this membrane and only the tips of the gemmules show free 

 dendritic protoplasm. 'The number of end-bulbs (one on 

 each terminal branch) of the association and ascending fibers 

 from the lower regions is not numerous, seldom exceeding six 

 or eight, and the form is that of an arborization of the nerve 

 twig ; on the other hand the terminations from the collaterals 

 of the psychic cells are much more numerous on the final 

 branches and show the disposition of his Fig. i. 'The inter- 

 pretation of the objective existence of the terminal apparatus 

 of the nerve fiber can be made but in one way, namely, that 

 the impression conveyed from external sources to central cells 

 and from local cell to local cell, is not accomplished by a diffus- 

 ion of the excitation through the whole cortex, or even at vari- 

 ous points along the course of the finer branches of the axons, 

 but at single points, perfectly definite in their distribution, and 

 that these points are situated only at the extremities of the 

 nerve fiber, in the form of an histologically exact formation — 

 the bulbous ending of the nerve fiber — .vhich in itself consti- 

 tutes the sole and only means for the carrying over of the cel- 

 lular force from axon to dendron, and from cell to cell, and is 

 in entire conformity with the conception of Waldeyer of the 

 entity of the neuron, each cell standing as an unit in the ner- 

 vous formation, and only in continuity with others at definite 

 points. ' 



