440 CHARLES R. STOCKABD AND E. M. VICARI 



from the Boston terrier-dachshund cross, may an individual 

 with the Boston terrier head possess the typical dachshund 

 thyroid histology? This is aside from the question of whether 

 the thyroid gland within itself has the power to regulate the 

 conformation of the bulldog head. The simple fact at this 

 place is that pure line dogs with the bulldog- head seem to 

 have an accompanying distortion in histologic structure of 

 the thyroid. Both these structural symptoms may be parts 

 of a complex largely under pituitary or some other regula- 

 tion. The nature of their cause or causes can only be ap- 

 proached after attempting to ascertain whether the two symp- 

 toms arc necessarily inseparable. These statements are given 

 in order to avoid misleading the reader into thinking that 

 because we discuss head type in connection with thyroid 

 structure a causal relation is inferred. A modified pituitary 

 influence might induce the characteristic thyroid modification 

 and possibly also the distortion of head growth. Thus the 

 two alterations would necessarily accompany one another 

 ;is results from a common cause. 



THE SIGNIFICANCE OF ENDOCRINE QUALITY IN 



RELATION TO PHYSICAL TYPE IN BOSTON 



TERRIER-DACHSHUND HYBRIDS 



The Inheritance of Contrasted Histologic Patterns of the 



Thyroid and Their Correlation with Physical Types in 



Boston Terrier-Dachshund Hybrids 



It has been shown that in Boston terrier-dachshund hybrids 

 no relation between the proportional amounts of thyroid tissue 

 and the characteristic breed types can be established. We 

 shall now attempt to determine whether histologic qualities 

 of the thyroid are closely or directly related to the structural 

 peculiarities of the individual. 



A photomicrograph of a section of dachshund thyroid is 

 shown in plate 85 (fig. I), and a similar section from the 

 Boston terrier is shown in figure 2. We see again, between 



