492 CHARLES E. STOCKAED AND E. M. VICAEI 



ments were planned to include crosses between breeds of 

 various constitutions. The cross just considered involves con- 

 trasted stocks of dwarf size, while the endocrine glands next 

 to be examined are from a cross between two normal or full 

 sized breeds with somewhat different character modifications. 

 The reader is already familiar with the highly modified 

 head and body of the English bulldog, as well as with the 

 distorted histologic pattern of its thyroid gland. The basset- 

 hound and its thyroid of rather low activity have also been 

 described. There has been, up to now, no implication of a 

 causal relation or direct connection between the physical types 

 and thyroid patterns in these breeds; such interrelationships 

 could be fairly discussed only after examining other members 

 of the endocrine system. A further understanding should 

 result from a study of the genetics of glandular modifications 

 in the hybrid generations derived from crosses between these 

 dogs of contrasted type. 



THE INHERITANCE OF CONTRASTED HISTOLOGIC QUALITIES OF 



THYEOID GLANDS AND THEIE COEEELATION WITH PHYSICAL 



TYPES IN BASSETHOUND-BULLDOG HYBRIDS 



The somewhat detailed treatment of the histology of the 

 endocrine glands in the Boston terrier-dachshund cross pre- 

 sented in the previous chapter facilitates the discussion of 

 the glands in the bassethound-bulldog cross, which will be 

 given in as brief form as clarity permits. 



Figure 1 in plate 93 illustrates a section of the thyroid 

 gland from a prolific bassethound bitch, 277 9 . Although at 

 first glance this gland appears fairly active, it should be 

 noted that the colloid is cracked and brittle and the follicular 

 epithelium is low; both of these are characteristics of a 



PLATE 93 



EXPLANATION OF FIGURES 



Bassethound-English bulldog cross. The inheritance of thyroid histological 



patterns in first and second generation hybrids. 



1 Bassethound 277$. 3 F, 739^. 5 F, 1313^. 



2 English bulldog 120 <?. 4 F t 741 <?. 6 F., 1312 <?. 



