498 CHARLES R. STOCKARD AND E. M. VICARI 



Iii spite of the evidently hyperactive condition of these 

 peculiar thyroid glands, neither of the dogs showed any 

 well known symptoms of so-called hyperthyroidism. On the 

 contrary, they were fat and inactive, and although they had 

 an inherited shyness, were not nervous nor restless. There 

 was no tendency for exophthalmos, even when one discounts 

 the excessively loose drooping skin which overhangs the eye 

 and almost closes it from view, and in spite of the sagging of 

 the lower lid which exposes the red conjunctiva at the median 

 edge of the eyeball, the so-called haw well shown in the 

 bloodhound eye. 



Considerable evidence forces us to suspect that such thyroid 

 glands, in association with rather typically modified pituitaries 

 and probably other altered members of the endocrine system, 

 do not secrete an amount of thyroid hormone in excess of 

 the demand from the constitution concerned. We recognize 

 that these thyroid pictures in differently constituted indi- 

 viduals might very readily be associated with symptoms of 

 pathologic hyperthyroidism, but the fact remains that the 

 animals described above are not so afflicted in spite of the 

 high activity of their thyroids. 



Figures 4 and 5 (pi. 94) illustrate rather unique and inter- 

 mediate histologic patterns in the hybrid thyroids. Figure 4 

 shows a thyroid histology that is remarkably similar to that 

 of the non-related Boston terrier gland. The follicular epithe- 

 lium is cuboidal in form and moderately active. The follicles 

 are irregular in size and the colloid is hard and slightly 

 brittle. There is considerable interfollicular tissue as well as 

 nests of parafollicular cells. The dog from which this gland 

 was taken, 902 $ , was killed when 18 months old. The head 

 was partially bulldog in type, and the brain presented a 

 moderate degree of internal hydrocephalus, a fairly common 

 characteristic in the bulldog group. 



Figure 5 shows a thyroid section from a 14 months old 

 animal, 916 $ . This F 2 bassethound-bulldog hybrid is shown 

 from life in plate 19 (p. 97), and a photograph of his skeleton 

 in plate 20 (p. 99). In body form, this hybrid approaches 



