1905.] Distribution of Chlorides in Nerve Cells and Fibres. 169 



artificially produced, if in the living organ there were not a corresponding 

 disposition." 



Eanvier* found that in addition to revealing the annular bands of the 

 intersegmental nodes and the portions of the axon in their immediate 

 neighbourhood, the use of the reagent demonstrated the lines of Frommann 

 at the nodes and in their vicinity, the distinctness of the striation gradually 

 lessening with the distance from the nodes. He found also that the axis 

 cylinder at the node exhibited a biconical swelling (renflement biconique) the 

 substance of which blackened with the reagent. 



The silver reaction at the nodes is, according to Boveri,f between the two 

 contact surfaces of the cells constituting the neurilemma which meet at that 

 point. Further, a similar reaction obtains in the immediate vicinity of the 

 nodes under the medullary sheath. The silver precipitate, owing to the form 

 of the periaxial space at this point which it occupies, gives the figure called 

 by Eanvier the biconical thickening, and regarded by him as a normal 

 integral portion of the fibre. In Boveri's view the enlargement is a deposit 

 on, not in, the fibre. 



A third precipitate which Boveri found obtained wherever the reagent by 

 its action brought the fibrilk-e of the axon into contact. This does not occur 

 at definite points, but it is, as a rule, found at the nodes. This precipitate 

 allows the fibrillse to be recognized except where the periaxial precipitate 

 with which it is in contact is so marked as to obscure them. 



Begarding the lines of Frommann, Boveri holds that they are rings about 

 the axon, not in the same, but if the fibrillar structure obtains immediately 

 beneath each, then the precipitate penetrates the fibre and is deposited 

 between the fibrilhe. He rejects the view that the lines are due to a 

 preformed or pre-existing transverse lamination of the axon, because the 

 layers of the silver precipitate decrease in intensity with the distance from 

 the node and at the same time become separated by greater intervals from 

 each other. The most important fact which he found to tell against the 

 view is that discovered by A. Boehm, then an assistant in the histological 

 laboratory at Munich, who placed fine capillary glass tubes, filled with 

 filtered egg albumen, in a - 5 per cent, solution of nitrate of silver. This 

 diffused into the tube and caused a white precipitate which consisted, in 

 great part, of chloride of silver, disposed not uniformly through the lumen, 

 but in layers, like the lines of Frommann, separated by zones free from 

 precipitate. 



* ' Traite Technique d'Histologie,' Paris, 1875, p. 725 ; also ' Legons sur l'Histologie 

 du Systeme Nerveux,' Paris, 1878, p. 45. 

 t Loc. cit. 



