Hardestv, spinal Cord of the Emu. 95 



of the ligamentum longitudinale laterale {Ninni, Figs. 2, 3 

 and 4). It is practically in line and continuous with the nucleus 

 niarginalis major of the lumbar enlargement. Its largest cells 

 are about as large as those of the ventral horn and differ from 

 them in apparently having fewer processes. They are similar 

 in shape to those described by Kolliker ( '02 ) in the spinal 

 cord of the dove. They are embedded m a thin column of gray 

 substance more or less invaded by the surrounding medullated 

 axones. These cells too are markedly segmental in their dis- 

 tribution. Midway between the nerve pairs of adjacent seg- 

 ments they are very sparsely scattered, being found at the rate 

 of about one cell to every four or five sections. In the regions 

 of the segmental enlargements the nucleus is thicker and the 

 cells often occur two or three deep in it (see Fig. 2). Thus, 

 this longitudinal band of cells also takes part in the segmental 

 arrangement of the specimen. 



According to Sherrington ( '00 ) this nucleus appears to 

 have been first observed by Gaskell in the alligator in 1885. 

 Gaskell ( '88 ) mentions it in discussing the segmentation of 

 the spinal cord in the Sauropsida (crocodiles and birds) and re- 

 fers to it as a lateral-surface-group of cells which is as strictly 

 metameric as the cells of the dorsal root ganglia. The nucleus 

 was independently described by Lachi ('89) and Kolliker 

 ('01 ). Kolliker gave it the name Hofmann' sc/ier Kleinkem 

 in distiction from the nucleus marginalis major, which he called 

 Hofmann'scher Grosskern. In another paper Kolliker ( '02 ) 

 makes a comparative study of these nuclei, finding them in the 

 salamander, proteus, lizard, alligator, dove, and also repre- 

 sented in the spinal cord of young dogs. In the dove and the 

 15-day dog he shows the nuclei distinctly metameric, arranged, 

 especially in the former, in isolated groups of cells one on either 

 side of each segment. In the spinal cord of the emu the met- 

 americ groups are not so isolated and distinct as Gaskell and 

 Kolliker describe them in the alligator and dove, there being 

 occasional cells scattered between the segmental enlargements. 



The lumbar enlargement with its nucleus marginalis major 

 and the slender conus meduUaris are apparently quite similar 



