The relation between the spleen and the contents of platelets in circulating blood have for a long time now been admitted on purely clinical and empirical bases (therapeutic action of splenectomy in Werlhof's disease, thrombopenia secondary to primitive splenomegaly). Some series of researches carried out in the last few years seem to allow an experimental framing of this relationship and an interpretation of its nature.
In 1933 a series of researches on the subject was begun in the laboratory of this clinic. We1 were able to establish that extracts of spleen taken from patients affected by Werlhof's disease applied in highly concentrated doses injure the megakaryocytes in cultures in vitro of the bone marrow of guinea pigs. The extraction was performed with the technic used in extracting trephones and therefore contained the whole hydrosoluble fraction dissolved, and the other fractions were suspended or in emulsion. So up to a