118 ENDOCRINE GLANDS 



about 26 grams and from 11 to 15, 37 grams on the average. 

 According to these writers, the weights usually given are 

 erroneous, due to the fact that various illnesses influence 

 the weight of the gland. It quite rapidly becomes 

 atrophic when the nutrition becomes deficient, in various 

 types of infantile cachexia, and during acute infections: 

 measles, scarlet fever, diphtheria, etc. The histological 

 investigations of Roger and Ghika, of Lucien and Parisot 

 have shown the frequency of thymus lesions in the young, 

 indicating a marked degeneration of the gland. Next to 

 the physiological evolution and parallel to it there exists 

 a pathological evolution, which may affect the first. 



In spite of all this, it seems to be generally admitted 

 that the normal involution of the thymus does not begin 

 until between the 10th and 15th year. Until puberty it 

 grows regularly and then gradually regresses. 



The thymus is at the same time a lymphoid, blood 

 forming and internal secretion organ, for its removal in 

 animals causes a variety of symptoms. The functions 

 of the thymus which up to the present time have been 

 well established are: 



1. ACTION ON GROWTH AND DEVELOPMENT OF THE 

 SKELETON. This has been shown by the experiments of 

 Tarulli, Lo Menace, Basch, Lucien, Parisot, and U. Seli. 

 Animals in which the thymus was removed show a delay 

 in growth, a reduction in height and volume of the bones. 

 According to Basch, the bones are more flexible and trans- 

 parent than normal, due to a decrease in the calcium 

 content. According to Lucien, Parisot and U. Seli, 

 however, the calcium content remains normal and the 

 resistance of the bones is not decreased. The earlier 

 the animal is operated upon, the more marked the delay in 

 growth. There is practically no change if the animal has 

 reached its normal growth. 



