STEUCTUBE OF I^EETOUS SYSTEM OF MOLLUSCA. 179 



Notes on the Minute Strucbure of the ]N"ervous System of the 

 Mollusca. By J. Gtilcheist, M.A., B.Sc, Ph.D., Marine 

 Biologist to the Groverument of- the Colony of the Cape of 

 Good Hope. (Commuuicated by B. B. Woodwaed, F.L.S.) 



[Read 21st January, 1897.] 



(Plate 12.) 



The following additions to our knowledge of the nervous system 

 of the Mollusca is a first contribution to a more extensive and 

 comparative review of the subject. It is an account of some 

 definite results obtained by the use of methjleue-blue and more 

 especially of my experience with modern methods, wliich I deem 

 it desirable to place on record, as other investigators have expe- 

 rienced difficulty in the attempt to apply them to the study of 

 histology of the MoUuscan nervous system. In tbe prosecution 

 of the work I have been especially indebted to Dr. Bethe, wbose 

 intimate acquaintance with methylene-blue method and readiness 

 to impart information have been of the greatest assistance. 



Method. 



Though a good deal can be done with ordinary methods 

 towards demonstrating the finer brandies of nerve-cells and the 

 course of nerve-fibres in Mollusca, it is necessary to use either 

 the method of Grolgi or the methylene-blue method to obtain 

 good results. Of the two methods, that of Grolgi seemed to be 

 the most promising ; but while Eetzius (6) and Samassa (8) have 

 used it successfully on tbe Pulmonata, they have found it in- 

 applicable to marine Mollusca. 



Joubin (7) has obtained a coloration of the nervous system of 

 some cephalopods by injection of methylene-blue, but apparently 

 without noting if this was a differential stain for cells. 



Having observed, by former trials with methylene-blue that 

 there was evidently a differential staining of the fibres of the 

 nerves, it seemed to me probable that means could be found of 

 further applying this beautiful method to the Mollusca, both 

 terrestrial and marine. Accordingly, after a few unsuccessful 

 attempts with the Grolgi method, I returned to the methylene- 

 blue, and, after many failures, at last obtained some satisfactory 

 results. 



I need not mention the various difficulties met with, or how 



-LTS^. JOUEN. — zoology, YOL. XXVI. 13 



