THE CENTRAL NERVOUS SYSTEM OF PROTOP- 

 TERUS ANNECTENS. 



Karl Rudolf Burckhardt, Ph.D., Assistant in the Labora- 

 tory of Anatomy, University of BerHn. 



Of the former investigators, who have dealt with the central 

 nervous system of Protopterus annectens, only one, namely, 

 Fiillignet, considers the microscopical anatomy. The work of 

 this author is in many respects incomplete, especially as com- 

 pared with the descriptions of the anatomy of other vertebrate 

 brains. I have, therefore, ventured to subject it to another in- 

 vestigation. 



The spinal cord shows the following structure : The dispo- 

 sition of the white and gray matter is as in Amphibia, in the 

 anterior horn are found very large ganglion cells, the processes 

 of which extend dorsad into the white substance, large cells are 

 also found in the lateral portion of the gray substance. For the 

 first time in the development of the animal kingdom, a substan- 

 tia gelatinosa of Rolando is seen. Isolated neuroglia cells are 

 found in the white substance, giving support to the fibres. The 

 nerve roots pass out alternately, as has been often noticed in 

 many of the lower vertebrates. A ligamentum denticulatum is 

 found on each side of the cord. 



The medulla oblongata is very simple in its structure and 

 shows a slight flexure. From it are given off the following 

 nerves : 



1 . The hypoglossal, with two ventral roots ; 



2. The vagus, with seventeen roots, of which three are 

 ventral and fourteen are lateral ; 



J. The glossopharyngeal, with two large roots; 



4. The fasiali-acusticus, with six roots ; 



5. The trigeminus with two roots. 



The cerebellum is composed of a fold similar to the one 

 found in the amphibia, though a little better developed. The 

 nervi trochlearis and abducens, which have hitherto been unno- 

 ticed in the Dipnoi, were also found. 



