. Elementary text-book of zoology. VERTEBRATA. 407 fourth ventricle. The part in the optic lobes becomes con- stricted into a small canal or iter leading from third to fourth ventricles. Fig. 293.—Diagram of the Vertebrate Brain. (Mainly after Huxlev.) Cerebrum. Pineal Body. Optic Lobe. Cerebellum. Spinal Notochord. Fig. 294. — Diagram- matic Median Section THROUGH a Vertebrate Brain, showing the The dorsal wall of the thala- mencephalon is produced into a process called the pineal body, which, in some cases, shows evidence of being a vestigial eye. The ventral wall is also
. Elementary text-book of zoology. VERTEBRATA. 407 fourth ventricle. The part in the optic lobes becomes con- stricted into a small canal or iter leading from third to fourth ventricles. Fig. 293.—Diagram of the Vertebrate Brain. (Mainly after Huxlev.) Cerebrum. Pineal Body. Optic Lobe. Cerebellum. Spinal Notochord. Fig. 294. — Diagram- matic Median Section THROUGH a Vertebrate Brain, showing the The dorsal wall of the thala- mencephalon is produced into a process called the pineal body, which, in some cases, shows evidence of being a vestigial eye. The ventral wall is also produced into a process called the infundi- bulum, coming into relation with the pituitary body (); the lateral walls become thickened and form the optic thalami. Thus the brain becomes a com- plex organ consisting of a linear series of specialised portions; but a further complication takes •place in the flexure of one part upon another. In the highest types (mammals) the brain is twice flexed upon itself and its origin from a single tube is thus disguised. From the brain there arise at least ten pairs of cranial nerves which are remarkably constant in their relationship. The fore-brain gives rise to the olfactory (I.) and optic (II.), the mid-brain to the oculomotor (III.) and trochlear (IV.), arid the hind-brain to the trigeminal (V.), abducens. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Masterman, Arthur Thomas. Edinburgh, E. & S. Livingstone
Size: 2295px × 1089px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookcollectionbiod, bookdecade1900, bookyear1902
