264 Frederick Tilney, 



brain in such a manner that the saccnhir eminence of tlie tuber 

 cinereum rests in it as one saucer in another. In the freshly removed 

 brain this part of the glandular tissue is seen extending- as far for- 

 ward as the optic chiasma. It imparts a grayish pink color to this 

 area. In its caudal portion, the ventral surface of the pars tuberalis 

 is fused with the pars distalis. Its dorsal surface is in contact with 

 the saccular eminence, except for a small opening through which the 

 infundibulum passes ventrad to reach the infundibular process. Its 

 lateral borders are reflected in such a manner as to completely invest 

 the free lateral extremities of the saccular eminence; while its thickened 

 caudal surface rests in the angle between the infundibulum and cor- 

 pora mammillaria in contact with the small pre-raammillary area v^^hich 

 forms a part of the floor of the third ventricle. The pars tuberalis 

 is fused with the eminentia saccularis throughout its entire extent by 

 means of connective tissue and epithelial processes as well as by 

 blood vessels and nerve fibers. A reconstruction of this portion of 

 the gland is shown in plate VI, fig. 4, and indicates how exactly the 

 structure conforms to the shape of the saccular eminence; the median 

 aperture at the junction of its ventro- cephalic and caudal surfaces 

 permits the passage of the infundibulum ventrad to reach the infundi- 

 bular process. Its histological character distinguishes it from the 

 pars infundibularis and pars distalis. 



The pars infundibularis (plate V, fig. 1, 13) completely invests the 

 infundibulum and infundibular process, to both of which it is firmly 

 attached. It fuses with the pars tuberalis without any sharp line of 

 demarcation, but is completelj^ separated from the pars distalis (plate V, 

 fig. 1, 14) by the interposition of the residual lumen (plate V, fig. 1, 15). 



The pars distalis is at no point in contact with the neural 

 portion. By its convex surface it forms the part of the hypophysis 

 which rests in the sella turcica. The arrangement of these several 

 portions of the gland is best seen in a reconstruction of a 70 mm cat 

 fetus (plate VII, figs. 5 and 6). 



From the relations of the neural and glandular tissues of the 

 hypophysis it appears that three elements pertaining to the fioor of 

 the third ventricle compiise the neural portion of the organ, i. e. the 



