462 CHARLES It. STOCKARD AND E. M. VICAKI 



not be misunderstood as confusing the problems of tissue 

 mass and hormone production. 



The study of the microscopic* structure of the F._, pituitaries 

 might supply evidence of qualitative differences in cellular 

 composition, indicating- differences in hormone production 

 among these glands. Such differences might also he corre- 

 lated with certain type differences in bodily form, as well 

 as with modifications in both structural and functional quali- 

 ties of the thyroid and other glands. More than thirty F 2 

 pituitaries were studied from these standpoints. Surprisingly 

 wide histologic variations occur, these supplying material for 

 analyzing the interrelations of pituitary deviations with the 

 already discussed modifications in physical expression. 



Among the F 2 Boston terrier-dachshund hybrids, we have 

 already found that contrasted ancestral characters may be 

 re-sorted in such ways as to give almost typical Boston 

 terrier and dachshund individuals in the same litters, as 

 well as specimens exhibiting various strange combinations 

 of the breed characters, and still others showing many modifi- 

 cations and intergradations between them (see plates 30 and 39, 

 pp. 129 and 236). We have just presented histologic evidence 

 showing that the pituitary glands from the two breeds tend 

 to differ very constantly and definitely in their microscopic 

 constitutions, and our next step is to determine whether the 

 F 2 hybrid approaching the Boston terrier in type will also 

 possess a pituitary gland inclining towards the histopathology 

 of that found in the pure Boston terrier stock, and, conversely 

 if there is any correlation between dachshund body type 

 and gland histology. 



With the idea that any relation between pituitary histology 

 and bodily type would be most easily recognizable in a com- 

 parison of glands from dogs showing completely contrasted 

 characters, we selected in the first place two pituitaries, one 

 from an almost perfect Boston terrier-like F 2 and the second 

 from a well expressed dachshund typed F L .. Figures 1 and 

 2 in plate 89 illustrate the pituitaries from two such op- 

 posite typed F._. Boston terrier-dachshund hybrids. Figure 



