97 



nucleus; flhils Pi^.5o represent?; the dlstpibution of the cells 

 more in letail ->n the right siie. 



These neurones are the largest of any in the nervous or- 

 ganization of Mustelas. The size attained by the cell-body 

 may be as great as 60 micra in transverse diameter by 100 mi- 

 cra lengthwise. The group, therefore, presents a very stri- 

 king picture in the field of the aiicroscope. The forois assuni- 

 ei by the celL-bodies are someAfhat diverse, ranging from ovyil, 

 through irregular outlines to a considerably elongated condi- 

 tion. The longer axis lies parallel, or nearly so, with the 

 limitans interna. 



In a thick section, the dendrites appear as tv»o or three 

 stout processes vrhich push their /vay into the nervous matter 

 dorsal to tne group and are soon lost to view. Those cells 

 lying very close to the median plane send their axones to the 

 opposite side; but the remaining members of the group, compri- 

 sing nearly all of the cells, have their axones extending away 

 from the mid-line. The axones from the several cells of the 

 same side, together v»ith the crossed axones, run laterally for 

 a greater or less distance, tarn anteriorly, and become associ- 

 ated into bundles which constitute a fairly well-marked tract 

 (Pigs. 20 and 55, r.n.t.). This tract extends forwarl to the 

 anterior limit of the midbrain, where it unites with its fello* 

 from the opposite side, and tne united group of fibres emerges 

 from the midbrain roof to penetrate the aqueduct of Sylvius 

 as the fibre of Seissner. The ultimate destination will be 



