136 GLANDS IN HEALTH AND DISEASE 



recent work tends to the opinion that it functions 

 throughout life. After the second year of life it 

 grows less in size. Here are some figures : At 

 birth, 13.26 grams (approximately 30 grams equal 

 one ounce) ; between one and five, 33 grams; be- 

 tween six and ten, 26 grams ; 11 to 15, 37 ; 16 to 20, 

 25; 56 to 65, 16; 66 to 75, 6. 



Function of the thymus. What the function of 

 the thymus is is a matter of constant debate. A 

 number of experiments point to the fact that its 

 activity is connected with that of the sex glands; 

 that the thymus, for a time, checks the development 

 of the reproductive organs. For example, the re- 

 moval of the thymus (in animals) is said to ac- 

 celerate sexual development, though it delays 

 growth; and castrated animals show an enlarged 

 thymus. 



Uhlenhuth, of the Eockef eller Institute, has spon- 

 sored the theory that the thymus secretes a tetany- 

 producing substance (see the chapter on the para- 

 thyroid) which is neutralized by the parathyroids. 

 Some claim that the thymus is the principal reserve 

 organ for nucleoprotein, an important type of pro- 

 tein particularly abundant in the nuclei of cells. 

 Still others deny that the thymus is an endocrine 

 gland. For example, Hopkins, in an exhaustive re- 

 view of the subject, says: "The evidence in favor 

 of such a theory (that the thymus is a ductless 



