MEDULLA OBLONGATA OF THE RABBIT. 



21 



age of the embryo. The older the embryo, the deeper it is 

 buried within the medullary wall. At the same time, I 

 have in no case been able to find it in the Randschleier. 

 This leads me to suppose that the oval bundle and tractus 

 solitarius are not homologous. That at least a portion 

 of the oval bundle is continuous with the tractus solitarius 

 cannot be doubted. 



Figure 16 represents the tractus solitarius in its course 

 through the medullary wall of 

 the medulla. On the one hand, 

 it is seen connected with the 

 oval bundle of the cord, and 

 it will be particularly observed 

 that it is here situated in the 

 Eandschleier. On the other 

 hand, it can be followed until 73 

 the bend of the medulla gives us 

 its fibres in cross-section iTS'). 



The Rhomboidal Lip. 



In all the transverse sec- 

 tions of the medulla of embry- 

 onic rabbits that I have made, 

 I have in no case seen any sign 

 of the rhomboidal lip. This 

 was a very great disappoint- 

 ment to me, for certainly noth- 

 ing can be more beautiful than 

 His's description of the mor- 

 phology of the human medulla 

 oblongata. 



Fig. 16. 



An oblique section of tlie lower 

 region of the medulla and the cervical 

 region of the spinal cord of an em- 

 bryo rabbit 11.2 mm. OB^ oval 

 bundle. TS^ tractus solitarius. TS'^ 

 fibres of the tractus solitarius in cross- 

 section. 



