458 CHARLES R. STOCKARD AND E. M. VICAEI 



Boston terrier pituitary react as definite genetic characters 

 in hybrids between these two breeds. 



Tlie liistopatliology of the pituitary in the F l generation of 

 Boston terrier-dachshund hybrids. From the foregoing sec- 

 tion one is forced to admit that in spite of the many varia- 

 tions concerned, the pituitary of the Boston terrier is far 

 more pathologic in structure than is this gland in the dachs- 

 hund. This can be said with even greater emphasis of the 

 thyroid glands of the two breeds (cf. fig. 2, pi. 82 and fig. 3, 

 pi. 84). Nevertheless, by crossing these pure breeds a well 

 proportioned, vigorous I\ hybrid is produced (see photo- 

 graphs from life in plate 29, p. 127). The hybrid is func- 

 tionally normal and a prolific breeder. Four F x females have 

 whelped sixty-five offspring from Fj sires. 



The pituitary glands from five F l hybrids were closely 

 examined at autopsy and later studied histologically. All 

 have cysts in the anterior pituitary, some of which could be 

 seen at autopsy with the unaided eye as distinct blisters 

 along the ventral surface. This fact is readily appreciated 

 by referring to the photomicrograph of a sagittal section 

 through the gland of F x 1293, shown in plate 88 (fig. 5). 

 This pituitary is riddled with enormous cysts which almost 

 completely crowd out the pars tuberalis and much of the 

 pars distalis. The arrested epithelial linings of these cysts 

 greatly reduced the amount of normally differentiated pitui- 

 tary tissue, yet the pituitary secreted sufficient quantities of 

 the specific hormones to maintain normal functions in this 

 dog until it was killed at almost 5 years of age. This animal 

 sired four litters of four or five puppies each. The pituitary 

 function in such an animal clearly shows that the full amount 

 of glandular tissue in the pars anterior is not an item of 

 importance, and that for normal life performances only a 

 fraction of the usual amount is necessary as long as the 

 quality of these secretions is normal. 



Photomicrographs of longitudinal sections of four F x Boston 

 terrier-dachshund pituitaries are shown in plate 88. All are 

 rather long and flat in general shape, as is common for the 



