653 



dorso-mediallj and dorso-laterally from the lar^e body (fig. 6). That 

 these groups belong to the vagus nucleus we learn from the sections 

 immediately frontal from the calamus, where it is seen that the 

 nucleus enlarges in the above direction by means of cells, which unite 

 with these cell groups. Also the ventro-lateral point stretches further 

 out (fig. 7); not unfrequently this is broken, so that the most distal portion 

 appears as a separate cell group. On this level many cell groups have 

 as many as c.c. 200 cells. Further frontally the ventro-lateral point 

 disappears, the dorso-lateral one becomes thicker, till the nucleus is 

 triangular in form with a broad base in the direction of the ependyma. 

 Now two or three independent cell-groups frequently appear in the 

 latero-dorsal portion, sometimes quite separate from the chief imcleus, 

 again connected with it by a few cells, (fig. 8) These can be seen 

 even when the chief nucleus has become considerably smaller, 

 which takes place at first medially ; simultaneously the number of 

 cells in the whole nucleus decreases, so that it becomes looser. 

 According as the nucleus decreases in size, the cell-type becomes 

 smaller, till finally this cell-type, for this nucleus is a large one, is no 

 longer seen in the ventro-lateral, i.e. the oldest, portion. In the 

 giraflPe it is remarkable that 20 sections more frontally from the 

 place where the dorsal motor vagus nucleus entirely disappeared, 



Ventriculus 



M 



■ ■■■■ ' -r 





Fig. 8. 



