No. I.] BLOOD CORPUSCLES. 73 



these organs begin to lose their haematopoietic function, some 

 of the nucleated red corpuscles found in them are carried in 

 some way to the marrow, where they form centres of growth 

 for similar cells throughout life. Bizzozero, like Neumann, 

 thinks that the red marrow alone possesses this function dur- 

 ing extra-uterine life, but, unlike Neumann, he believes that 

 the spleen may temporarily resume its blood-forming functions 

 after severe hemorrhage when the marrow alone is unable to 

 regenerate new corpuscles with sufficient rapidity. As evi- 

 dence for this statement he publishes experiments made by 

 himself (19^) and also in connection with Salvioli, in which it 

 was shown that, with dogs and guinea-pigs, nucleated red cor- 

 puscles can be found in the spleen of the adult if the animal 

 has been subjected previously to a severe bleeding, or, better, 

 to a number of successive bleedings : under such conditions, 

 not only were the simple nucleated forms found, but nucleated 

 cells in process of division by karyokinesis. In man, also, 

 after death from anaemia there are several cases recorded in 

 which nucleated red corpuscles have been found in the spleen 

 (Foa [22], Pellacani). On the other hand, Neumann (5/^) contends 

 that even after severe hemorrhage nucleated red corpuscles are 

 not found in the spleen, or are found in such small numbers 

 that their presence may be accounted for by the fact that they 

 occur also in the circulating blood, especially in the vena 

 azygos, which brings back blood from the red marrow of 

 the ribs. With reference to this last point, it is undoubt- 

 edly true that in the blood of animals after severe and re- 

 peated hemorrhages, nucleated red corpuscles may be found, 

 and similarly in the human subject it is known that in per- 

 nicious anoemia, leukaemia, etc. {Osier and Gardner [23], 

 Laache [25]), nucleated red corpuscles may be found in the 

 circulation. But it must be borne in mind that in the spleen 

 of animals after strong hemorrhage one may find nucleated 

 red corpuscles in cases when they are absent from the general 

 circulation ; and furthermore they may occur in the spleen in 

 large numbers, and showing every sign of an active multiplica- 

 tion. Neumann (5/^) himself admits that in one case in which the 

 animal (dog) had been bled a number of times, and in which 

 septic infection had developed, he could find nucleated red 

 corpuscles in the spleen, but not in the circulating blood. He 



