TERMINATION, OP NERVES IN THE LIVER. 445 



by the solution of the excess of the fixed gold, this process of 

 course being carefully watched. In this reagent one finds an 

 additional advantage ; the nerve-fibres are the last to part 

 with the violet colour, thus being distinguished from connec- 

 tive-tissue fibres. It, however, does not always operate in the 

 latter way satisfactorily. 



The sections of the human liver received from the gold a dull 

 violet or a dull red tint, while in other preparations a blue violet 

 tint was found. In two cases I obtained preparations which to 

 the eye appeared almost colourless, but which on examination 

 demonstrated the nerve-fibres very distinctly. 



All the sections were cleared in oil of cloves, and mounted in 

 balsam. 



In the study of the ultimate terminations of the nerves I 

 have used the Leitz ~ inch homogeneous immersion with special 

 illumination. In the human liver, more especially, it was 

 impossible to do anything with a less efficient objective. In 

 the Necturus liver it was quite easy, however, to see the 

 required structures with a system 7 of Leitz, but I have 

 endeavoured in every case to verify my observations with the 

 higher power objective. 



The value of gold chloride as a reagent for difi'erentiating 

 nerves is not admitted by all histologists. It has been urged 

 also that the elements it selects in a fresh tissue and those it 

 differentiates in a tissue hardened by a reagent such as chromic 

 acid are not necessarily the same structures. This objection 

 has a great deal of force, especially in view of the fact that gold 

 chloride gives a violet tint to connective tissue which has been 

 first hardened with chromic acid ; the corium of Necturus and 

 the connective tissue around arteries are cases in point. More- 

 over, the tendency of a hardened tissue is to reduce equally the 

 gold so as to give to all the tissue elements a violet colour. Yet 

 with all its faults the method of hardening with chromic acid 

 and the subsequent treatment with gold chloride has many 

 advantages over other micro- chemical and staining reagents, 

 and so far as the demonstration by it of nerve-structures 

 are concerned no greater suspicion should be attached to results 



