154 



MR HAROLD AXEL HAIG ON THE 



VII. THE HISTOLOGICAL FEATURES OF THE VERMIS OF THE CEREBELLUM. 



(Text-fig. 6.) 



A section across the lamellar of the vermis (or of the hemisphere) shows the typical 

 arrangement characteristic of higher mammals, viz. a white centre, an inner layer of 

 '"granules" (small nerve-cells, the axons of which pass peripherally), an intermediate 

 layer of the large flask-shaped cells of Purkinje, the axons of which pass centrally, the 

 dendrons passing peripherally, and a superficial "molecular" layer, consisting of small 



m 



Fir:. 6. A portion of a vertical section of the vermis of the cerebellum, x 6. 



/. Fibres of the white centre. 

 m. Molecular layer. 

 p. Layer of large Purkinje colls. 



</. Layer of granules (small nerve-cells and axons 

 of the Purkinje cells). 



nerve-cells, the dendrons of Purkinje cells and fibres derived from neuroglia cells, and 

 the " climbing" and " moss" fibres coming from the deeper layers. 



The only point of comparative value is the relatively large size of the Purkinje cells ; 

 these are not only large, but exist also in greater numbers than are usually met with in 

 an equivalent area of the human type. 



[The uncinate gyrus and optic chiasma present much the same features as the same 

 regions in the human type : no points of comparative value were made out in the 

 sections.] 



PART II. 



THE HISTOLOGY OF THE PITUITARY GLAND. (PI. II. and Text-figs. 7, 8, 9.) 



The pituitary gland of the Weddell seal is a body of considerable histological 

 interest, inasmuch as all three portions are well developed, and in addition there occurs 

 upon its upper aspect a small portion of tissue the structure of which is not represented 

 in the human pituitary.* 



The gland (text-fig. 7) is a large one, and is made up of three main portions, viz. 



* It is possible that this structure is represented in some of the lower types by the sacci vasculosi found in 

 connection with the pituitary gland. 



(ROY. soc. EDIN. TRANS., VOL. XLVIII., 862.) 



