438 CHARLES R. STOCKARD AND E. M. VICARI 



of the cocker spaniel, although the gland of the spaniel may 

 be all in all somewhat more active. The point of interest is 

 that the skull of the cocker, with its mild degree of basi- 

 cranial chondrodystrophy, might be classed as the least pro- 

 nounced of the bulldog series, and the round cranium as- 

 sociated with the long muzzle of the dachshund makes it an 

 aberrant member of the long headed breeds. The dachshund 

 falls near the end of the long-head series and the cocker 

 spaniel stands at the beginning of the bulldog head group. 

 The histologic patterns of their thyroids are similar, though 

 as far as our knowledge goes this is mere coincidence. 



Figure 4 (pi. 84) illustrates the histologic structure of the 

 great Dane thyroid. This specimen was obtained from a 

 bitch more than 7 years old. The follicles are large and the 

 abundance of secretion droplets indicates a vigorously active 

 epithelium without symptoms of hyperthyroidism. It will be 

 particularly noticeable in this section that the epithelial cells 

 on the left side of the follicles from which the droplets would 

 seem to be exuding are higher and have more cytoplasmic 

 material than the cells in other places where no drops are 

 being formed. The extensive study of thyroids from several 

 hundred dogs closely observed during life convinces one that 

 the secretion droplets are a most reliable indicator for thyroid 

 activity, although it is realized that some investigators using 

 limited and less favorable material would question this. Lying 

 among the large follicles of the Dane thyroid are very small 

 follicles readily seen surrounding the oval bits of colloid, 

 particularly in the right half of the photomicrograph. The 

 presence of these tiny follicles is most unusual in a gland 

 with well developed, large and typical follicles. Parafollicular 

 cells are not abundant and the total epithelium is involved in 

 the follicular formation. 



The thyroid of the giant great Dane is not very different 

 from that of the St. Bernard (pis. 82 and 83). Both have large 

 follicles and are usually fairly active; but the very tiny 

 follicles have been found only in the great Dane. 



