Near. — Nervous Syst. Squalus. 
PLATE 9. 
Stages in the development of the abducens nerve. All the specimens were 
killed with Davidoff’s fluid (corrosive-acetic). All Figures are from frontal sections 
except Figure 65. 
Fig. 62. A frontal section of an embryo with 62 somites (9 mm.). Magnified 450 
diameters. Two roots are present. 
Fig. 68. From an embryo with 68 somites (10 mm.) magnified 285 diameters. 
The course of the nerve is very direct in this stage, at least in the 
specimen figured. Throughout the most of its course it is entirely 
free from nuclei. 
Fig. 64. A combination from 7 sections of an embryo with 80 somites. Three 
roots present on the side of the embryo figured. Deeply staining nuclei 
appear in close connection with the nerve, and there is some (in my 
opinion doubtful) evidence of the migration of nuclei to or from the 
neural tube. Peripherally the nerve divides into fine fibrille. Magni- 
fied 200 diameters. 
Fig. 65. A cross section of an embryo with 75 somites in the region of the 
posterior root of the abducens, magnified 285 diameters. Evidence of 
migration of nuclei (?). 
