STUDIES OF THE LYMPHATIC TISSUE

1. On subcutaneous infection of rabbits with staphylococci of low virulence there appears at the place of injection first a hemorrhagicpurulent inflammation and later a localized purulence. In the regional lymph nodes there is lymphatic hyperplasia, and in the blood a lymphocytosis. 2. In the regional lymph nodes there is first a regressive change of Flemming's secondary nodules and of transition forms. Then follows lymphatic hyperplasia, starting apparently from solid secondary nodules and progressing by way of pseudo-secondary nodules to a diffuse lymphoid hyperplasia. The increase of lymphocytes in the blood parallels this development. 3. Only after the highest point of the lymphocytosis has been reached or passed do we find the first Flemming's secondary nodules, which thereafter increase in number and size while the number of lymphocytes in the blood falls, and reach their maximum development when the number of lymphocytes in the blood is again normal. Therefore, the original conception of Flemming that the site of formation of the lymphocytes of the blood is in Flemming's secondary nodules, cannot be accepted. 4. The lymphocytes of the blood originate in the pseudo-secondary nodules as in embryonic life. The mother cells of the lymphocytes would appear to be Marchand's proliferating endothelial (reticular) cells.