SYMPATHETIC SYSTEM IN BIRDS 



295 



3. Ganglion of Remak 



The ganglion of Remak arises about the middle of the fourth 

 day, .as an oval cell-column lying in the mesentery just dorsal to 

 the rectum (fig. 5, g.r.). Its greatest diameter occurs in the pos- 



mes~ 



Fig. 6. Transverse section of an embryo through the sacral region of an embryo 

 of the chick (130 hours incubation), X 110. ao., aorta; g.r., ganglion of Remak; 

 hyp., hypogastric plexus; mes., mesentery; r., rectum; sp.n. spinal nerve. 



terior region. It increases in size very rapidly until at the close 

 of the fifth day it has become a large and conspicuous column of 

 closely aggregated cells, with a maximum diameter of about 85 

 micra (fig. 6, g.r.). Its diameter decreases anteriorly until it 



