165 



On the Distribution of Chlorides in Nerve Cells and Fibres. 



By A. B. Macallum, M.A., M.B., Ph.D., Professor of Physiology, and Miss 

 M. L. Menten, B.A., Assistant-Demonstrator of Physiology, in the 

 University of Toronto. 



(Communicated by Professor W. D. Halliburton, F.R.S. Received July 24, — 



Read December 14, 1905.) 



[Plates 2—4.] 



CONTENTS. 



PAGE 



T. — Introduction 165 



II. — Historical Account of the Literature of the Subject 167 



III. — Methods of Investigation 172 



IV. — Results 175 



A. In Nerve Fibres 175 



B. In Nerve Cells 186 



V. — General Remarks 188 



I. — Introduction. 



The question of the composition of nerve fibres, and especially of the axon 

 itself, is one which must be solved before a rational explanation of the 

 properties of nerve tissue can be given. The solution of the problem in its 

 ultimate details is possible only when we have at our command reagents 

 and methods which will greatly exceed in sensitiveness those which are 

 accessible to us at present, for such as have been used hitherto comprehend 

 only those of ordinary chemical analysis, and they have not thrown any 

 light on the subject, while those of micro-chemistry, which have been 

 employed up to the present, involve staining with dyes such as one employs 

 in histological technique and treatment with nitrate of silver and osmic 

 acid. The last-named reagent is of service in demonstrating the fat of the 

 medullary sheath, and the nitrate of silver has been employed to show the 

 nodes of Ranvier and the striation known as Frommann's lines, a result 

 which, as will be shown, depends on a micro-chemical reaction, but the dyes 

 hitherto used have revealed little except structure. There are, indeed, the 

 Weigert h<ematoxylin and the Golgi reactions, but the constituents of the 

 sheath and axon responsible for both are unknown. Through these and 

 other histological methods much has been ascertained regarding the structure 

 of nerve fibres and cells, but so far little has been determined which will 

 serve to explain such properties as irritability and conductivity and the 

 nature of the nerve impulse itself. 



VOL. LXXVIT. — B. N 



