LITERARY NOTICES. 



Edinger L. Ueber das Gehirn von Myxine glutinosa. Aus dem Anhang zu den Abhandluiigen der 

 Kon'tgl. Preuss. Akad. der Whsenschajten vom Jahre 1906. Berlin. 1906. 36 pp., 3 plates. 



The results are based largely upon the new fiber method of BiELSCHOWSKY, 

 which however, Edinger finds it necessary to modify for Myxine by leaving the 

 heads to be studied much longer in the silver solution — as long as 30 days. The 

 method gives a histological picture which is more like that of certain invertebrates 

 than of other vertebrates, differing even from Petromyzon and Amphioxus. Espe- 

 cially in the forebrain and thalamus, there is a much smaller number of cells and 

 fibers and the fibers are finer than in any other vertebrate. The tissue between 

 these cellular elements appears in these preparations as a very fine fibrous reticulum. 



In the discussion of the morphology of the forebrain Edinger distinguishes 

 two divisions of the cerebral hemispheres, (i) a ventral, the hyposphaerium, which 

 receives the olfactory nerves and contains internally the striatum and nucleus of 

 origin of the taenia thalami; and (2) a dorsal, the episphaerium, containing the pal- 

 lium. On the basis of his more recent work (and also that of Kappers which was 

 published in January, 1906, in this Journal), he has receded from his former posi- 

 tion on the morphology of the pallium in fishes and adopted the view of C. L. Her- 

 rick and Studnicica that the fish brain does not consist exclusively of hyposphae- 

 rium but contains at least the beginnings of an episphaerium, though in an abnor- 

 mal position. The obscurity regarding the ventricles of the forebrain of Myxine 

 is at last satisfactorily cleared up by the discovery of actual cavities or definite 

 epithelial vestiges m all of the places where other vertebrates possess forebrain 

 ventricles. 



The cerebellum is said to be totally absent, a statement which suggests an inter- 

 esting field for inquiry in the exact relations of cells and fibers in the somatic sen- 

 sory centers of the oblongata from which the cerebellum of other vertebrates has 

 quite certainly been derived phylogenetically. 



The plates include an excellent series of cross-sections through the medulla 

 oblongata, but the author has been able to unravel but few" of the fiber complexes 

 and to identify few of the structures, remarking, "to cumber the literature with 

 a new description whose basis is no better established than that of earlier authors 

 would be to no purpose. . . . Doubtless it will be possible later, when the fish 

 oblongata is better known, to study more closely and to identify the relations of the 

 fiber tracts shown for the first time in these very accurately drawn figures. " This 

 illustrates very clearly the opinion long held by the reviewer, that the fundamental 

 plan of structure of the nervous system can best be discovered by an exhaustive 

 comparative study of a large number of types in which the systems in question are 

 very diversely developed rather than by exclusive attention to primitive or generalized 

 species. Having discovered the fundamental vertebrate plan of each functional 

 system, by the comparison of forms where it attains maximal and minimal develop- 

 ment, then this schema can be read back with ease into the primitive and unspecial- 



