1. The spleen is not an indispensable, vitally important organ for the guinea-pig, since that animal bears splenectomy without loss of health, developes normally, and gains well in weight.
2. The hypertrophy and hyperplasia of the lymph glands, particularly of the mesenteric glands, which develop after the operation correspond to a lymphocytosis, which makes its appearance in the course of the first year after the operation so constantly that it may be looked upon as a characteristic sign of the absence of the spleen. This increase may amount to double and more. We must therefore assume that the deficiency of splenic function may be met by the lymphatic glandular system. This period of lymphæmia may doubtless in some animals persist for years in exceptional cases; in the majority, however, the lymphæmia diminishes in the course of the first year, and indeed subnormal quantities of lymphocytes may then be produced.
3. The cells of the bone-marrow, on the contrary, and the polynuclear pseudoeosinophil cells do not show the least variation in the course of the first year. Bearing in mind that under normal conditions these cells are met with exclusively in the bone-marrow, and that inflammation in animals after removal of the spleen is accompanied by an acute pseudoeosinophil leucocytosis, exactly as in normal animals, one must admit that the production and function of this kind of cell are quite independent of the spleen. Hence there can be no doubt about their myelogenic nature.
4. It is especially important that the mononuclear and the leucocytes associated with them, undergo no increase. As these cells under normal circumstances occur both in the spleen and in the bone-marrow, we must assume that normally also the bone-marrow is responsible for the majority of this kind in the blood, and that the deficiency in the splenic contribution can be easily covered by a slightly raised activity of the bone-marrow. Were the share of the spleen important, from general biological considerations, an over-production of the kind of cell in question must occur in the vicarious organs.
5. The increase of the eosinophil cells, which constantly makes its appearance in the second year after the operation, is highly interesting, and leads to a really enormous rise in their absolute and relative numbers. Their percentage number once rose to 34.6%, and their absolute quantity amounted at the end of the second year on the average to 30-50-fold their original number (see table).
Hence it follows from Kurloff's researches that the spleen of the guinea-pig plays quite an unimportant part in the formation of the white blood corpuscles, and that after splenectomy in the first year compensation occurs only in the lymph-glands, followed in the second year by a great increase of the eosinophil cells. It is to be particularly insisted once again that the spleen has nothing at all to do with the formation of the pseudoeosinophil polynuclear cells, which are the analogues of the polynuclear neutrophils of man.
How do observations on man stand in the light of Kurloff's observations, which might be regarded as depending on peculiarities of the particular kind of animal?
Completely analogous material is afforded by cases, in which in healthy people a splenectomy has been necessary in consequence of trauma. Unfortunately the material available for this purpose is extremely rare; and it would be of the utmost value if the alterations of the blood in such a case were systematically studied for a period of years. We have ourselves begun our observations in two patients directly after the operation, but were unable to continue them, as death occurred within the first week after the extirpation. Up to the present only seven cases of rupture of the spleen with subsequent splenectomy have been published, as is stated in the collection of cases of v. Beck. In two only, of these seven cases, one of Riequer's (Breslau) the other of v. Beck's (Karlsruhe) was a cure effected. Through the courtesy of the above-mentioned gentlemen, we were able to investigate specimens from these two patients.
In the case of v. Beck the operation was performed on June 15, 1897. We received a dry blood preparation about 6 months after operation. Investigation showed a considerable lymphæmia: the bulk of the lymphocytes belonged to the larger kinds: the eosinophil cells were certainly not increased. For other reasons an exact numerical analysis could not be undertaken. We hope to be able to follow the further course of this case.