232 THE INTERNAL SECRETIONS 1920 



16. Constant chilliness. 16. Unbearable sensation 



17. Difficult and slow of heat, 

 respiration. 17. Superficial respira- 



18. Increase in weight. tion, slight expansion 



19. Senile appearance, of thorax. ^ 

 even in young people. 18. Loss of weight. 



19. Youthful, luxuriant 

 development, at least 

 in the earlier stages. 



One can see from this table how diametrically op- 

 posed to each other are the symptoms produced. In 

 fact, we have before us two different types of individ- 

 uals, whose physical and mental contrasts cannot, in- 

 deed, be more outspoken. While the symptoms enumer- 

 ated in the left-hand table are produced by extirpation 

 of the thyroid gland, we find more or less similar symp- 

 toms in cretins and myxedematous patients, whose 

 thyroid gland is either atrophied or destroyed. On the 

 other hand, when we consider the fact that artificial 

 Graves's disease was induced experimentally by feed- 

 ing individuals with the desiccated product of the 

 gland, there can be hardly any doubt that this chain of 

 different symptoms is produced in the first instance by 

 the lack of the thyroid hormone ; and in the second, by 

 its overabundance. 



It is clear that this thyroid hormone now isolated in 

 chemical form by Kendall, exerts a powerful influence 

 over the metabolism and nutrition of the organism, 

 hence upon its growth and normal development. The 

 normal senility and old age, like the premature senility 

 of myxedema, might be the result of the same etiolog- 

 ical factor, namely, the lessened activity of the thyroid 

 gland. 



In this connection we will cite again- from Biedl (2) 

 a very interesting passage : "The foundation for the 

 theory that old age results from changes in the thyroid 

 gland lies in the fact, commented upon by Horsley, that 



