404 CHARLES R. STOCKARD AND E. M. VICARI 



tional size of thyroid gland tissue varies very greatly among 

 apparently normal adult dachshunds, and that the relative 

 size of the gland very probably has little to do with deter- 

 mining the type, since the seven animals are closely alike 

 in form. In other words, so far as influence on body form 

 is concerned, the amount of thyroid material is not an im- 

 portant factor. 



The series of bars at the left in text-figure 80 indicates 

 relative thyroid sizes for thirteen adult English bulldogs, six 

 bitches and seven males. The thyroid sizes of these animals 

 show an enormous range, from 55 milligrams per kilogram 

 of body weight to 305 milligrams per kilogram. The largest 

 relative amount of thyroid is almost six times greater than 

 the smallest and this difference is quite independent of sex. 

 It is also important to note that bulldog 120 6 , with the 

 smallest relative amount of thyroid tissue, was as true and 

 as strong an expression of his breed type as was 903 S or 

 885 9 , two of the dogs having the largest relative amounts 

 of thyroid tissue. All these animals had been selected for 

 their exaggerated expression of bulldog type. No. 885 2 , hav- 

 ing the largest amount of thyroid, is shown in plate 54 (p. 290), 

 and 903 5, a champion type, is seen in plate 18 (p. 93). The 

 dog 120 S , with the smallest amount of thyroid, could have 

 been mistaken for either of these two. It is quite evident 

 that an enormous variation of as much as 600% in propor- 

 tional amounts of thyroid tissue does not modify the direc- 

 tion of type expression in these extremely distorted animals. 

 Again we see, therefore, that the gross proportional amount 

 of thyroid is not an important factor in determining either 

 the degree or quality of thyroid function in the dog breeds. 



The second group of bars in text-figure 80 represents the 

 proportional sizes of thyroid glands in nine bassethounds, 

 three of which were immature animals only 5 or 6 months 

 old. Thyroid glands are proportionally larger in puppies 

 than in adult dogs and the three highest bars represent the 

 three immature bassethounds. The six other bars represent 

 adult thyroids ranging from 160 to 370 milligrams per kilo- 



