GENETIC TYPE AND THE ENDOCRINES 489 



The sections of the parathyroids in plate 92 seem much 

 less pathologic in structure than do either the thyroids or 

 the pituitaries from the same animals. Figure 2, from 524 $ , 

 presents the typical double row cellular cords or tubule 

 arrangements of the principal cell epithelium, and there are 

 localized regions where the cytoplasm of the cell cords stains 

 somewhat darker, as if more concentrated or in a different 

 phase of activity. In some of these places the parallel align- 

 ment of the cells disappears and the cells appear to he of 

 the bluish type. There is nothing in the histology of this 

 parathyroid section that would lead one to anticipate the 

 extreme histopathology shown by the accompanying pituitary 

 and thyroid glands (pis. 86 and 90). 



The photomicrograph of the parathyroid from the sister, 

 525$ (fig. 4, pi. 92), shows congestion of the vessels near 

 the hilum of the gland. This gland presents again a fairly 

 normal histologic picture, and the general behavior of the 

 animal gave no evidence of parathyroid disfunction. 



Summary and Deductions 



The foregoing examination of the parathyroid glands com- 

 pletes the survey of the histologic qualities of the endocrine 

 glands from the parental stocks and the hybrid generations 

 of the Boston terrier-dachshund cross. Only three members 

 of the endocrinic system have been included in this survey. 

 The general functional quality of the gonadal secretions in 

 these several generations is very well indicated by our rather 

 extensive breeding records, but these will not be discussed 

 at this time since the present consideration has been restricted 

 to those glands more largely concerned with growth patterns 

 and modified structural types. The discussion of the supra- 

 renal glands in the different breed types is also reserved 

 for a later report, since it is difficult to relate clearly their 

 influences to the modifications of structural types and be- 

 haviors now being reviewed. Reference to the thymus is 

 almost completely omitted; we merely record that the mass 



