THE THYMUS 



It is widely believed that the thymus is an organ The position 

 of internal secretion and is intimately connected with 

 the development of the body and of the reproductive 

 functions. It is probable that once genital activity 

 is established the thymus rapidly undergoes atrophy, 

 and plays no part in the metabolism of reproduction. 



Hoskins 1 , whose attitude towards unproven state- 

 ments and to generalizations in regard to the functions 

 of the organs of internal secretion is always sturdily 

 antagonistic, denies that there is any evidence for or 

 against the view that the thymus is a hormonopoietic 

 gland. He doubts whether it is more than a lymphoid 

 organ, and states that there is a steady decrease in 

 the "percentage of lymphocytes in the blood, from 

 61 per cent, at one year to 23 per cent, at puberty 

 (14*8 years)". Pappenheimer 2 , in a critical review of the 

 literature and of his own experiments, expresses a similar 

 view. Personally, I am inclined to think that while, 

 strictly speaking, the thymus is not an organ of 

 internal secretion in the sense that the thyroid and 

 other glands are, it has, like the mammae, a definite 

 relationship, more or less indirect, to the production of 

 somatic and genital maturity. It is not necessary at 

 this point to press the acceptance of the view that the 

 individual somatic and genital metabolism are inter- 

 dependent. 



1 Hoskins, E. R., Endocrinology, 1918, vol. ii, p, 241. 



2 Pappenheimer, A. M., Trans. Amer. GynecoL Soc., 1917, vol. 

 xlii, p. 113. 



