184 



FRED W. STEWART 



three-quarter day rat embryos are relatively much farther ad- 

 vanced than the 6-mm. pig embryos figured by Kuntz (the period 

 of gestation in the rat averaging but twenty-one days), neither 

 silver impregnations nor v. Rath preparations give any indication 

 of the presence of neuroblasts surrounding the esophagus, as 



G.S.N. X 



Fig. 5 Rat embryo, 15| days, von. Rath's technique 

 gastric branches of the vagus. Projection drawing, X 500. 



Neuroblasts along 



the anlage of myenteric and submucous plexuses. The fibers, 

 to be sine, are present, but up to the present nerve cells have 

 not been encountered in any such relation. Considering the 

 excellent impregnations which have been obtained of the corre- 

 sponding gastric and intestinal plexuses, there is little reason 

 for supposing thai tlie failure to demonstrate them in a peri- 

 esophageal position is due to faulty technique. 



