THE ADRENAL GLANDS 87 



in its weight. Back in 1858, the pioneer student of the thymus, 

 Friedleben, declared that the size and condition of the thymus is 

 an index to be the state of nutrition of the body. Underfeeding 

 for four weeks will reduce it to one thirtieth the normal. It 

 seems to act as a storage and reserve organ, affording some 

 protection against the limitation of growth by lack of food 

 material. In exhausting or wasting disease, the weight of the 

 gland sinks much more quickly than other glands. Scattered 

 instances have been reported of children growing, putting on 

 inches in height and expanding mentally, when thymus was fed 

 to them, in whom every other measure previously tried had 

 failed. A French study of over four hundred idiotic children 

 with normal thyroids reported that over three fourths had no 

 thymus at all. Everything points to the most direct and close 

 relation between the gland and nutrition and growth, but with 

 nothing tangibly definite like our knowledge of the thyroid and 

 the pituitary. 



There is evidence that the thymus is involved in the health and 

 efficiency of muscle cells and muscularity. Certain tumors of the 

 thymus, presumably destructive of the gland substance proper, 

 and thus cutting off its secretion, are accompanied by a singular 

 muscle weakness and atrophy of the muscle cells, entirely out of 

 proportion to the general damage suffered by the other cells of the 

 body when affected by the poison of a malignant growth. Also, 

 the thymus has been discovered diseased in certain mysterious 

 progressive muscular wastings. A remarkable fatigability of 

 muscles, which appears after the slightest exertion, is a feature. 

 The feeding of thymus has caused muscle cramps which appar- 

 ently depends upon an increased excitability of the muscle nerve 

 endings. 



Feeding of thymus to some of the lower* creatures of tlie animal 

 kingdom will completely hold up differentiation. Take the un- 

 folding of the specialized tissues and organs which transform the 

 tadpole into the frog and the chrysalis into the butterfly. A 

 tadpole kept supplied with enough thymus in a nutrient medium 

 will swell into an extraordinary giant tadpole, but will not change 

 into a frog. Recently, this experiment has been contradicted. 

 Yet this effect corresponds to the conception of its importance in 

 childhood as a retardant of precocity, physical and mental. 

 Clinical observations emphasize that in childhood it is the chief 

 brake upon the other glands of internal secretion which would 



