156 THE NEK VOUS SYSTEM. 



nective-tissue capsule, derived from the pia mater ; this encloses an 

 irregular mass of epithelial cells ; according to de Graaf a twig" of 

 the ramus supramaxlllaris reaches it subcutaneously, and a blood- 

 vessel accompanies the pedicle through the foramen pariétale. Ac- 

 cording to Darkschewitschj the pedicle contains medullated nerve- 

 fibres derived directly from the brain. 



The pituitary body (Figs. 102, 103 Hi/) when examined with 

 a lens is seen to consist of two portions : an anterior, superior, and 

 smaller white jDortion, and a larger, inferior, posterior, and reddish 

 portion. The anterior portion has the form of a very small, flat 

 disk, and is enclosed in a connective-tissue capsule which sends 

 in larger and smaller processes. In either transverse or longitu- 

 dinal section it is seen to be formed of two horizontal layers 

 separated by a line of blood-vessels and connective-tissue. The 

 upper layer consists of a granular and reticular matrix, containing 

 many nuclei (averaging 0'oo6 to 0*010 mm. diameter), and divided 

 into irregular rounded or polyhedral spaces by bands of tissue 

 derived from the capsule. This layer is more vascular than the 

 lower. The lower layer consists of a mass of clear, nucleated 

 rounded or polyhedral cells (o-oi6 to 0*024 mm. in diameter; 

 nuclei from o*oo8 to 0*0 12 mm. in diameter, Reissner)^ pierced 

 by very fine connective-tissue septa derived from the capsule. 

 The septa are, for the most part, vertical and longitudinal 

 (Reissner), the blood-vessels are very few. 



The posterior larger portion of the pituitary body (Fig. 106) is 

 also compressed from above downwards, and in transverse section 

 as an oval outline. It possesses an external thin connective- 

 tissue capsule, which sends in fine processes to support a mass 

 of convoluted tubes, between which course a few blood-vessels ; 

 these tubes possess an outer nucleated basement-membrane, and 

 are lined with a single layer of more or less cylindrical epithelium, 

 which entirely fills the tube; hence the tubes possess no lumen. 

 The tubes are from 0*04 to 0*08 mm. in diameter ; the cells are 

 clear or granular, and possess distinct, rounded nuclei. 



e. The Cerebral Hemispheres and Olfactory Lobes. The 

 cerebral hemispheres {Lohi hemisphaerici, Stieda ; Lobi cérébrales, 

 Heissner ; Centralmasse des Geruchssinns, Carus ; Hemisphaeren 

 des grossen Hirns, Tiedemannj Grosse Hemisphaeren, Schiess ; 

 Prosencephalon, Huxley). The olfactory lobes [Ttihercula olfac- 

 toria, Stieda ; Lohi olfactorii, Reissner ; Riechkolben, Schiess ; Rhi- 

 nencephalon, Huxley). 



