LITERARY NOTICES. 



Bing, Robert, and Burckhardt, Rudolf. Das Centralnervensystem von Ceratodus forsteri. 

 Gustav Fischer, Jena. 1905. Reprinted from Semon's Zoii/ogische Forschungsreisen in 

 Australi'en und dem Malayischen Archipel. 



This paper, which is dedicated to Professor Edinger, consists of two parts, a 

 purely descriptive part by Dr. Bing and a comparative part by Professor Burck- 

 hardt. The first part includes brief descriptions of the external form of the brain, 

 its relations to the surrounding cranial structures, the ventricles the histology of 

 the various regions as revealed by h^emalum preparations, and the embryological 

 development of the brain. 



The second part begins with a comparison of Ceratodus and Protopterus. 

 After an exhaustive analysis of their characters. Professor Burckhardt concludes 

 that it is scarcely possible to affirm that either of these brains is more primitive than 

 the other. He rightly dismisses this comparison as of far less importance than 

 the question: Do the structures and relations of the brains of Ceratodus and 

 Protopterus correspond with what we already know of the phylogenetic relationships 

 of these forms in general. Then follows a comparison with Polypterus, Acipenser 

 and Scymnus. The author lays great stress (possibly relatively too great) on 

 growth-strains and other mechanical or non-nervous factors in shaping the forms 

 of the brains of the lower fishes, as opposed to the direct response of the central 

 nervous system to its peripheral sensory and motor functional dependencies. He 

 certainly has made a very important point in emphasizing the necessity of consider- 

 ing in each case the brain in its relation to the organism as a whole. While, there- 

 fore, the brain may be taken as a fairly reliable index of phylogenetic values in a 

 group like the selachians where the types follow in closely seried ranks, it is quite 

 otherwise in the ganoid-dipnoid phylum, where we have scattered survivals of a 

 rich fauna now nearly extinct. Here, on account of differences in mode of life and 

 diversity of past phyletic history of the few surviving types, phylogenetic specula- 

 tions based on the brain can have small value except as controlled by the whole 

 mass of phyletic records — anatomical, embryological and palaeontological. 



Professor Burckhardt recurs to the thesis which he developed several years ago 

 so forcibly in his "Bauplan des Wirbelthiergehirns," that the broad resemblances 

 from which the phylogenetic relationships of the larger groups are most clearly 

 deduced are to be found in the non-nervous parts of the brain rather than in parts 

 which have been highly specialized for particular functions. But, like most of the 

 other comparative neurologists, of Europe, he seems not to have an adequate appre- 

 ciation of the fact that in evaluating the significance of the positive adaptive dif- 

 ferentiations of the nervous substance the real units are not the traditional arbitrary 

 transverse divisions of the brain, but the functional systems. These primitive 

 reflex systems, like the ventricular and ependymal landmarks which Burckhardt 

 uses so effectively, are very constant in fundamental plan; and yet the whole of the 

 evolutionary history of the vertebrate nervous system can be read in terms of their 

 progressive or regressive modifications. 



c. J. H. 



