In spite of the repeated demonstration that the thymuses of healthy, well nourished children are prominent and average 20 Gm. or more in weight and that wide thymic shadows on roentgenograms of infants' chests are common, the belief persists that these findings represent a constitutional susceptibility to death from trivial causes, i. e., status thymicolymphaticus, and account for most respiratory symptoms of infancy. Because of the tenacity of these misconceptions, I have undertaken to demonstrate their fallaciousness first by a review of the normal growth phenomena of the thymus and of its reaction to disease and inanition, second by a graphic presentation of these phenomena from additional data, and third by a comparison of the statistics from the new data with those obtained by previous workers.
INVOLUTION AND GROWTH PHENOMENA
According to Jackson,1 various earlier workers recognized that the thymus and lymphoid tissue, like other organs, atrophied with inanition.