648 O. D. ANDERSON 



sociated with body conformation and build. Generally speak- 

 ing, it was found that the tall, thin, narrow-chested dogs 

 showed a great deal of muscular activity and were very alert 

 to all stimuli. They tended to be ' ' nervous ' ' and flighty. The 

 conditioned reflexes could be easily elicited, often by the slight- 

 est stimulation, and were very stable when once established. 

 The general pattern is that of a restless and highly nervous 

 animal. This behavior is typical, for example, of the German 

 shepherd. On the other hand, the short-legged, stocky and 

 wide chested dogs are not usually hyperactive and alert. The 

 conditioned reflexes were elicited from them with difficulty, 

 even by strong stimulation, and even then were very unstable. 

 The behavior pattern is that of a calm or phlegmatic animal. 

 The bassethound is a good example of this type. 



What is the underlying nature of such fundamentally dif- 

 ferent modes of behavior ? The earlier chapters in this volume 

 have presented evidence which shows that body build is 

 closely associated, through the operation of genetic principles, 

 with the glands of internal secretion. For example, the thyroid 

 and pituitary of the German shepherd are histologically dif- 

 ferent from the thyroid and pituitary of the English bulldog. 

 Similarly, these glands are modified in characteristic manner 

 in the bassethound and in the St. Bernard. Differences in 

 the histology of the same gland in different breeds may be 

 interpreted as signifying possible differences in the level or 

 quality of the secretory activity of the gland. This suggests 

 also that the characteristic types of behavior seen among 

 the various breeds might be dependent upon differences in 

 glandular quality and activity. 



The present experiments were undertaken to study this 

 question. We considered it desirable to study the effect of 

 critical alterations in the internal secretions (administration 

 of hormone substances and operative removal of glands) 

 upon the behavior of a group of pedigreed dogs exhibiting 

 the degree of behavioral reaction classified by James as 

 intermediate or ''mid-type." These dogs were neither highly 

 nervous nor very phlegmatic, but were an almost intermediate 

 blend of the two extreme types. 



