GENETIC TYPE AND THE ENDOCTUNKS 429 



be directly charged with the growth conditions in the head 

 of the bulldog'. The bassethound thyroid illustrated in the 

 photomicrograph was functioning somewhat more actively 

 at the time of death than that of the foxhound. This was 

 due entirely to chance, and these two glands are, as a rule, 

 about equally active, or, if there is a difference, the foxhound 

 lias the more active thyroid. After fixation the colloid in the 

 bassethound thyroid is hard, and usually as brittle as in 

 the foxhound. 



The thyroids from two other breeds with short bulldog-like 

 heads are illustrated by figures 1 and 2 in plate 82. Figure 

 1 shows the Pekingese thyroid to be quite bulldog-like, with 

 small irregularly shaped follicles separated by abundant extra- 

 follicular tissue. The follicular epithelium is in places high, 

 columnar and quite active, forming a peripheral circle of 

 secretion droplets about the colloid. The colloid, after fixa- 

 tion, is rather soft, indicating its freshness. There are extra- 

 follicular epithelial cells and small nesls of parafollicular 

 cells lying between the follicles. This gland, as a whole, gives 

 a fairly typical picture of so-called hyperactivity of the 

 thyroid. There are no important indications of developmental 

 arrest and the adenomatoid symptoms seen in the English 

 bulldog are absent. The appearance and behavior of the 

 Pekingese is also quite typical of the hyperthyroid individual. 

 The animal is nervous, restless and excitable, with marked 

 exophthalmos. 



Figure 2 (pi. 82) illustrates the histology of the Boston 

 terrier thyroid. This gland has small, irregularly shaped, 

 hyperactive follicles. The hyperactive condition is shown in 

 five of the Boston terrier thyroids examined, and in the case 

 of the sixth individual, which was killed after a few day's 

 illness, thyroid activity had ceased and the follicles are lined 

 with low cuboidal epithelium. The latter specimen is shown 

 in plate 85 (p. 443) and is from 76 9. This case is a good 

 illustration of how promptly a general illness tends to arrest 

 the hypersecretion of the thyroid. The colloid in the Boston 



