No. I.] BLOOD CORPUSCLES. I07 



at the same time tliere was usually a diminution in the total 

 proteids of the blood. As far as it goes, this result is in accord 

 with the hypothesis that the fibrinogen is formed from the 

 liberated nuclei of the nucleated red corpuscles. I have in 

 progress other experiments for the purpose of further testing 

 the hypothesis. 



The HcBmatopoietic Function of the Spleen. 



All the facts bearing upon this question have already been 

 stated in various parts of this paper. It may be convenient, 

 however, to bring them together in the form of a brief statement 

 of the different views held. It is well known and universally 

 admitted that for a certain period during embryonic life, the 

 spleen takes part in the formation of red corpuscles, as is shown 

 by the fact that numerous nucleated red corpuscles, some of 

 them in the act of multiplication, may be found in it. Shortly 

 after birth, the spleen no longer contains nucleated red cor- 

 puscles and for this reason the majority of writers who believe 

 that these cells are the predecessors of the ordinary red cor- 

 puscles, have concluded that under normal conditions the spleen 

 during extra-uterine life takes no further part in the production 

 of new red corpuscles. This function is relegated entirely to 

 the red marrow. On the other side, a number of investigators, 

 while admitting the absence of nucleated red corpuscles from 

 the spleen under ordinary conditions, have nevertheless classed 

 it with the lymph glands under the head of the haematopoietic 

 organs, because they hold that the colorless corpuscles from 

 which the nucleated red corpuscles are formed are produced in 

 this organ. The most elaborate form of this theory is found 

 in the works of Lowit (29) upon the origin of the erythroblasts, 

 an account of which is given in the historical review. For my 

 own part, I have not been able to convince myself that erythro- 

 blasts are continually forming in the spleen or lymph glands, 

 as I have not been able to get any intermediate stages between 

 them and the nucleated red corpuscles, and therefore take sides 

 with those who think that the red marrow is the only organ as 

 yet discovered, in which new red corpuscles are produced dur- 

 ing post-natal life. This statement applies, however, only to 

 the spleen under ordinary conditions of life. Bizzozero (19) 



