GENETIC TYPE AND THE ENDOCRINES 435 



spherical crania and much reduced facial skeletons. One of 

 these is the Brussels griffon, in which the face is practically 

 flat with no protruding muzzle, the most extreme reduction 

 in jaw structure found among the dogs. The head and face 

 of the Brussels griffon resemble much more closely these 

 parts in a small monkey than in another dog. The second 

 midget breed to which w r e refer is the ancient Maltese poodle. 

 Here the cranium is spherical and the face is attenuated by 

 protruding forward as a narrow and almost cylindrical muz- 

 zle. Such heads cannot be truly interpreted as of bulldog 

 pattern, though they have in common the reduction of jaw 

 structure and mal-accommodation of the teeth. 



These two midget breeds show very similar conditions in 

 the histologic pattern of their thyroids, which differ very 

 much from that discussed for the bulldog, yet superficially 

 resemble it in certain respects. Figure 1 in plate 84 illustrates 

 the peculiar histology of the Brussels griffon thyroid. This 

 section is from a perfectly typed bitch of more than 7 years 

 of age, but it resembles almost exactly the familiar picture 

 of the newborn gland from either the human or the puppy. 

 There are a great number of follicles, all of which are very 

 small and some extremely minute. These are true size dif- 

 ferences among the follicles, as has been determined in serial 

 sections, and are not simple apparent differences due to cuts 

 through zones of various sizes. Some of the smallest bits of 

 colloid are seen to be surrounded by uniformly cuboidal 

 epithelium with no indication of tangential cuts through the 

 follicular wall as are shown in other places of the section. 

 There is an excessive amount of extrafollicular epithelioid 

 tissue without definite arrangement, as well as very tiny 

 follicles containing a mere drop of colloid. These conditions 

 give to the section a compact and much more densely 

 cellular appearance than is associated with the normal adult 

 thyroid and its larger follicles. 



It will be recalled that the Brussels griffon is inclined to 

 rest and sleep much of the time, but when in action to be 



