Proc. Boy. Socy. of Edin. ] 
[Vol. XXX. 
Fig. 1. — A, posterior ganglion spinal cord ; 
B, migrating nerve cells. (End of second day.) 
Fig. 2. — A, sympathetic nerve cells lying behind 
the aorta ; B, aorta. (End of third day.) 
Fig. 3. — A, aorta ; B, sympathetic nerve cells 
and fibres in front of the aorta. (Fifth day of 
incubation.) 
Fig. 4. — Sympathetic nerve cells and fibres in 
the mesentery. (Fifth day.) 
Dr Willtamina Abel, 
[Plate I. 
