THE NERVOUS SYSTEM 131 
brain weight at 425,25 grs., the relative weight of the latter 
would be 1: 220 (Moller). 
A comparison of the cerebral surface shows that Man 
differs from the Anthropoids in the preponderance of the 
frontal lobe (/7., Figs. 78-82) and, to a lesser degree, of the 
occipital lobe (oc.), and in a corresponding backward extension of 
the temporal lobe (¢p.). The parietal lobe (pa.) is about equally 
developed in the brains of Man and of Anthropoids (Moller). 
Since this subject has so far been, comparatively speaking, 
little investigated, and since our knowledge of the functional 
ch. 
iy if 
zd. 
Fic, 83.—HYPotTHETICAL MEDIAN-LONGITUDINAL SECTION THROUGH THE SKULL 
AND BRAIN OF A VERTEBRATE EmBrRyo. (Partly after Huxley.) 
cr’., basis cranii; ch., chorda dorsalis ; cr”., roof of the skull; na., nasal cavity; c.h., 
cerebral hemisphere, with the corpus striatum (c.s.) lying basally, and the olfactory 
lobe (o/.) anteriorly ; 7.0., thalamencephalon (fore-brain), which has been produced 
dorsally into the pineal gland (ep.), and basally into the infundibulum (7/.), hp., the 
hypophysis. Anteriorly, the base of the optic nerve (op.) is seen, and in the lateral 
wall the position of the optic thalamus is indicated (th.) ; c.p., posterior commissure ; 
m.b., mid-brain ; /.6., hind-brain ; ¢.c., canalis centralis. 
significance of the different regions of the brain is still far from 
complete, no general conclusions as to the possible correlation 
of these differences with mental peculiarities can be drawn. 
The slight projection of the cerebellum from below the 
edges of the occipital lobes in Anthropoids, is due less to the 
narrowness of the latter than to the striking breadth of the 
cerebellum itself (Moller). Even in man the occipital lobes do 
not always completely cover the cerebellum, but in this matter 
considerable variation occurs. 
Special interest attaches to the pineal gland (epiphysis cerebri) 
(ep., Figs. 84 and 86) which arises in the region of the roof of 
the fore-brain. 
In the lower Vertebrates this organ either lies free or is 
embedded in a depression or foramen (parietal foramen) of the 
* It must be left to future investigators to prove whether the topography of the 
course of the fibres in the optic chiasma given by Joh. Moller for Anthropoids, 7.e. 
the constant occurrence at the surface of certain groups of fibres, has a parallel in 
Man (perhaps in embryos or the lower races). 
