224 



ALBERT KUNTZ 



CLLGr 



Fig. 4. Transverse section of the neural tube and the anlage of the sym- 

 pathetic trunk of an embryo 11 mm. in length, X 125. 



evidence of the migration of medullary cells from the neural tube 

 is found in embryos about 4.5 mm. in length. At this stage the 

 neural crest is not yet differentiated into ganglia, but appears as 

 an inconspicuous ridge spreading laterally from the median dorsal 

 line of the neural tube. It is so inconspicuous indeed that in 

 many sections it may be distinguished only under favorable con- 

 ditions. In a few instances the fibers of the ventral nerve-roots 

 have penetrated the walls of the neural tube and are accompanied 



