Many diseases of the blood are associated with striking changes in the morphology of the spleen. Often, indeed, the gross change in this organ is the dominating feature of the clinical picture. Much has been written concerning these changes, but as yet little progress has been made in the attempt to correlate changes in the spleen with clinical symptoms.
There is considerable uncertainly about our knowledge of the functions of the spleen. That this organ has important functions, however, can hardly be questioned. There is, for example, considerable evidence to show that the spleen may have a marked influence on hemolysis. It is but a step then to assume that there may exist for the spleen conditions associated with a hyperactivity of some of its functions, let us say the function of influencing hemolysis. To such a condition the term "hypersplenism" may be applied. Conversely, a