UNDER-ACTIVITY OF THYROID 183 



eat at about the usual rate, he is almost sure to deposit 

 the surplus in his body in the form of fat. It is perhaps 

 not going too far to say that in general persons with a 

 tendency to obesity are persons in whom the thyroid 

 gland tends to be slightly less active than normal. 



Another symptom which displays itself, particularly 

 where the deficiency of thyroxin is marked, is a decrease 

 in the efficiency of the nervous system. Nervous and in- 

 tellectual sluggishness are evident, in severe cases being 

 so pronounced as to approach imbecility. There are sev- 

 eral human strains known in which the thyroid gland is 



Fig. 46. — Drawing from a photograph to show the appearance of 

 child, 23 months old, with deficient thyroid, and the same child after 

 administration of sheep's thyroid for 11 months. 



hereditarily either seriously defective or wholly inactive. 

 Children inheriting this deficiency are doomed from birth 

 to partial or complete idiocy if nature is allowed to take 

 its course. One of the striking medical triumphs of the 

 latter part of the last century was the discovery that ex- 

 tracts of the thyroid gland of meat animals could be ad- 

 ministered as a part of the diet to persons with deficient 

 thyroid, and that the body would thus obtain enough of 

 the hormone for its requirements. Complete cures have 

 been and are being wrought thus in cases in which de- 

 ficient thyroid is the only serious abnormality (Fig. 46). 



