334 Journal of Comparative Neurology. 



cation of the comparative method as insisted upon and en- 

 forced by the teaching and example of Prof. Wilder, of 

 Cornell University, and numerous European investigators. 



Although Rabl-Riickhard was the first to specifically 

 apply this method to fish brains in the satisfactory solution 

 of the homologies of the pallium, the same identifications 

 would have been made by any observer moderately familiar 

 with modern comparative data. The writer independently 

 recognized the same relations some time since, as doubtless 

 every student of fish brains has done, whether or not his eye 

 has met the works of Riickhard. 



With the discovery that the membranous pallium is the 

 specific homologue of the cerebral cortex of the higher verte- 

 brates, a large field of enquiry was opened, which has thus 

 far yielded comparatively meager resvilts. The questions as 

 to the fate of the commissure and tracts of the cerebrum, 

 as well as of the cellular elements proper to the cortex, yield 

 to none in neurology in far-reaching significance. 



Before entering upon these details, I shall be but fulfilling 

 a promise long since made in giving in detail the methods 

 employed. In making the description as detailed and precise 

 as possible it is by no means implied that all of these methods 

 are the best or most convenient, or that there is any special 

 significance in the exact proportions employed. But some 

 experience in laboratory practice has conclusively shown 

 that for a beginner no minutiae are unimportant, and no 

 latitude can be safely afforded to inexperience. The formulae 

 and directions given in histological hand-books very generally 

 omit what seem to their compilers self-evident precautions, 

 on which, in many cases, the success of the preparation 

 depends just as truly as upon the fundamental reactions 

 involved. 



It would seem to be an axiom that a method will be most 

 generally available which combines the necessary difterentia- 

 tion of tissues with the nearest approximation to the perfect 

 prervation of the essential details of each. Especially is this 



