238 ALBERT KUNTZ 



b.). From the tips of these growing fibers, cells pass in well 

 defined paths into the walls of the oesophagus. It is probable 

 that most of the cells which become separated from the vagi 

 wander out along the fibers of these growing branches. The cells 

 which have wandered into the walls of the oesophagus are not 

 arranged in well defined rings as yet, but are loosely scattered in 

 the tissues (fig. 13, m.s.p.). 



The fibers of the vagi do not yet extend beyond the region of the 

 heart. In transverse sections through the stomach, the paths of 

 the vagus branches are indicated by the presence of numerous 



rasp 



ox ft 6 ft J*&\ 



Fig. 13. Transverse section through the oesophagus and the vagus trunks in 

 an embryo 7 mm. in length. X 160. 



cells like those described above. These cells show a tendency to 

 spread until they have completely surrounded the walls of the 

 stomach. Similar cells are found scattered in the walls of 

 the intestine as far as the latter can be traced. Thus, it appears 

 that, having once become established in the anterior region of the 

 digestive tube, these cells migrate posteriorly along its course. 



That these migrant nervous elements found in the walls of the 

 digestive tube have migrated thither from the vagus trunks can- 

 not be doubted. There is no difficulty in tracing cells from the 



