Fig. 39. Section through the olfactory involution and part of fore-brain
of a larva on the ninth day after impregnation, shewing olfactory nerve.
Fig. 40. Section through the anterior part of the head of the same
larva, shewing pituitary involution.
Figs. 41-43. Transverse sections through an embryo on the eleventh day
after impregnation.
Fig. 41. Through fore-part of head, shewing the pituitary body still
connected with the oral epithelium.
Fig. 42. Slightly further back than fig. 41, shewing the pituitary
body constricted off from the oral epithelium.
Fig. 43. Slightly posterior to fig. 42, to shew olfactory involution,
eye, and hyomandibular cleft.
Fig. 44. Longitudinal section of the head of an embryo of 15 millims. in
length, a few days after hatching, shewing the structure of the brain.
Fig. 45. Longitudinal section of the head of an embryo, about five weeks
after hatching, 26 millims. in length, shewing the structure of the
brain. In the front part of the brain the section passes slightly to one
side of the median line.
Figs. 46 A to 46 G. Transverse sections through the brain of an embryo
25 millims. in length, about a month after hatching.
Fig. 46 A. Through anterior lobes of cerebrum.
Fig. 46 B. Through posterior lobes of cerebrum.
Fig. 46 C. Through thalamencephalon.
Fig. 46 D. Through optic thalami and optic chiasma.
Fig. 46 E. Through optic lobes and infundibulum.
Fig. 46 F. Through optic lobes and cerebellum.
Fig. 46 G. Through optic lobes and cerebellum, slightly in front of
fig. 46 F.