i66 



THE HUMAN SPECIES 



In structure the organ consists of a framework of connective 

 tissue furnished with cells containing pigment bodies, of striated 

 muscular fibres, blood vessels, nerve fibres and ganglion cells. 

 The so-called brain-sand, traceable in the parietal organ of the 

 Cyclostomata, and consisting of minute particles of carbonate 

 of lime, phosphate of lime and magnesia, which was formerly 

 considered of great importance, is found in man and in certain 

 of the mammals. Neither man nor any of the mammals pos- 

 sesses a foramen parietale, but Studnicka is inclined to regard 



< > 



FIG. 84. Epiphysis and surrounding parts of the skull of a child of twelve years. 

 Ep, Epiphysis ; R, Recessus pinealis ; Cp, Commiss. post. (Oppel, Vergl. 

 rnikr. Anat., Part v., Fig. 123.) 



the white parietal spot as well as the similarly placed pigmented 

 areas of certain animals (e.g., horse) as rudiments of a parietal 

 spot. 1 



In conclusion we must mention as parts of the brain those 

 cerebral nerves originating therein which, when completely 

 developed, consist of twelve pairs. In spite of a general corre- 

 spondence, certain distinctions are still to be noted between the 

 higher and lower Vertebrates. Thus in the fishes, amphibians, 

 birds and Monotremata, the nerves springing from the Bulbus 

 olfactorius unite into a trunk, whereas in the higher mammals 



1 Studnicka, loc. cit., i., 450. 



