GENETIC TYPE AND THE ENDOCRINES 465 



ments and also occasional small epithelial follicles. The aver- 

 age proportion of acidophiles to basophiles, as based on 

 counts through three regions in five longitudinal sections, is 

 about sixteen to one, and this relation is within the normal 

 range for dogs. 



A comparison may now be made between this pituitary 

 and one from an F 2 hybrid of contrasted type (shown by 

 photomicrograph of longitudinal section in figure 2 of plate 

 89). This gland was obtained from 355$, an F2 Boston 

 terrier-dachshund which was killed when 3 years old. The 

 animal had long legs and a Boston terrier head, with an 

 undershot, prognathous mandible. 



The general form of the pituitary in this animal is short 

 and thick, and in the longitudinal section it will be seen that 

 the wide and cystic pars distalis is too short to fold around 

 the distal end of the nervosa and cover its dorsal surface. 

 Tilney's simile of the ball in the catcher's glove is applicable 

 to this case. The pars nervosa is more richly filled with 

 nuclei and fusiform cells than in the dachshund-like section 

 (fig. 1). The intermedia is thicker and its cells invade the 

 nervosa more extensively, but it does not evaginate into the 

 substance of the nervosa at its distal end as in the dachshund 

 type. The cells of the intermedia show distinct cord-like 

 and follicular arrangements. The tissues of the pars tuberalis 

 and distalis are crowded out of normal position by the ex- 

 tensive and complex cystic formation. The cysts are lined 

 in many places with ciliated columnar cells and mucous cells, 

 some of which are of typical goblet form, which indicates 

 the persistent retention of their early embryonic nature and 

 the lack of a tendency toward differential development. Among 

 these extensive cysts one sees outlying masses of fully dif- 

 ferentiated pituitary epithelium consisting of the three well- 

 expressed characteristic cell types. The acidophiles occur 

 more abundantly toward the posterior end, and the basophiles, 

 which vary in staining reactions, are quite plentiful in the 

 middle region. The proportion of basophiles to acidophiles 

 is low, and the total number of these chromophilic cells is 



