142 



PHYSIOLOGY OF FARM ANIMALS 



[CH. 



showed muscular tremors, convulsions and emaciation. Similar 

 results occur in people afflicted with thyroid insufficiency. The 

 diseases due to this cause are known as cretinism and myxoedema. 

 The former of these occurs in children and is common in certain 

 parts of Switzerland but is not very infrequent in other countries, 

 including England. The individuals, who are known as cretins, 

 suffer from greatly arrested growth and deficient mental develop- 

 ment which may be very marked. Myxoedema, which affects 

 persons of mature age, is a disease of a similar character. The 

 sj-mptoms are loss of hair, nervous and mental deterioration, 

 and loss of memory which if not relieved by treatment are 

 followed b}^ premature death. The recognised treatment is 









l''ig. 68. Section througli thyruid gland (from Schafer). 



feeding on raw thyroid gland or on extract, the glands being 

 obtained from cattle or sheep. Thus the active substance of 

 thyroid is presumably the same in all mammals, and it can be 

 absorbed unaltered through the wall of the alimentary canal. 

 Feeding on thyroid gland removes or greatly mitigates the 

 symptoms due to cretinism, while myxoedema can often be com- 

 pletely cured. It is necessary however that the treatment should 

 be continued permanently, otherwise the patient lapses into the 



