A treatise on zoology . he Craniate is subdivided into primaryfore-brain, mid-brain, and hind-brain. Later on the hind-brain forms a posterior myelencephalon ormedulla oblongata, and an anterior metencephalon, giving riseabove to the cerebellum (Figs. 7, 8, 9, and 10). The hind-brain is 1 Authors differ on this debatable point. Some place the anterior eud of thebrain at the infuudibulum, others at the edge of the ueiiropore. Johnston [248a]believes it to lie at a point just behind the anterior commissure, and in front of theoptic recess and chiasma. 14 BRAIN the least modified part; it resembl
A treatise on zoology . he Craniate is subdivided into primaryfore-brain, mid-brain, and hind-brain. Later on the hind-brain forms a posterior myelencephalon ormedulla oblongata, and an anterior metencephalon, giving riseabove to the cerebellum (Figs. 7, 8, 9, and 10). The hind-brain is 1 Authors differ on this debatable point. Some place the anterior eud of thebrain at the infuudibulum, others at the edge of the ueiiropore. Johnston [248a]believes it to lie at a point just behind the anterior commissure, and in front of theoptic recess and chiasma. 14 BRAIN the least modified part; it resembles the spinal cord most closelyin histological structure, and from it emerge all the cranial nerves towhich a segmental value is usually attached, except the oculomotorand pathetic. It ahvays retains a considerable cavity, metacoele or4th ventricle. Its roof is never entirely nervous, and forms avascular membrane, the choroid plexus. The roof of the meten-cephalon becomes thickened as the cerebellum, which acquires a
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Keywords: ., bookcentury1900, bookdecade1900, bookpublishe, booksubjectzoology
