1. During the first three or four weeks after splenectomy hemoglobinuria due to hemolytic serum was not followed by jaundice.

2. One month and more after splenectomy the red cells had an increased resistance to hemolysis.

3. Three and a half months after splenectomy and even later, jaundice occasionally occurred spontaneously.

Attempts to explain these three phenomena have been based on the following possibilities: (1) that some function of the spleen is essential for the degradation of hemoglobin or for the elaboration of its derivatives; (2) that there is some interrelation between the spleen and the blood-forming organs or between the spleen and the blood-disintegrating mechanism, or perhaps both interrelations exist; (3) that there is a disturbance of the hemolyzing or bile-forming function of the liver dependent on the blood changes following splenectomy.

This multiplicity of problems and likewise of possible explanations has rendered the presentation of the explanatory work in one communication extremely difficult. In the interests of clearness, therefore, the various phases are dealt with in separate papers.