294 



ALBERT KUNTZ 



As incubation proceeds, the prevertebral plexuses assume more 

 definite proportions. The cells increase in number and become 

 more closely aggregated. At the close of the sixth day (144-hour 

 stage), nearly all the cells which were present in the primary 

 sympathetic trunks in the posterior region of the body have wan- 



1 i • •• ' i AM/ , f 



Dies. 



Fig. 5. Transverse section through the sacral region of an embryo of the chick 

 (105 hours incubation), X 60. ao., aorta; g.r., ganglion of Remak; hyp., hypogas- 

 tric plexus; mes., mesentery; nc., notochord; r. rectum; sp.n., spinal nerve. 



dered down into the prevertebral plexuses. Neither cells nor 

 fibers can be traced ventrally from the prevertebral plexuses as 

 yet except in the sacral region. Here numerous cells may be 

 traced from the hypogastric plexus directly into the ganglion 

 of Remak. 



