222 HUMAN PHYSIOLOGY 



lie closest to the passing stream are steadily evolved into 

 red corpuscles and when the transformation is complete 

 they detach themselves and drift away in the current. 

 The original cells of the red marrow have nuclei but none 

 can be discovered in the mature corpuscles. The hollow 

 centers strongly suggest the loss which has been suffered. 

 It is a curious fact that after severe hemorrhage, when 

 the system is taxed to restore the normal condition, 

 corpuscles with nuclei are often to be found in the blood. 

 Apparently, at such a time, corpuscles not fully developed 

 are impressed into service. 



The evidence goes to show that there is a fairly active 

 formation of red corpuscles and we must suppose that 

 there is a corresponding disintegration. Whether this 

 occurs here and there all over the body or in particular 

 places has been much discussed. Long ago it was 

 maintained that the spleen is concerned in the work of 

 destruction. The view fell into disfavor but has lately 

 been revived in a modified form. Removal of the spleen 

 in certain cases of anemia has proved beneficial, and it 

 is natural to explain such an observation by concluding 

 that the spleen had been destroying the corpuscles more 

 rapidly than the loss could be made good. 



It was stated in the previous chapter that the pigments 

 of the bile are derived from the coloring matter of the 

 blood. Wherever the dissolution of the corpuscles takes 

 place we must suppose that certain products are carried 

 in the plasma and sooner or later worked over by the 

 cells of the liver with the result that these waste-sub- 

 stances are separated. It is noteworthy that the pig- 

 ments of the bile do not contain iron ; this element seems 

 to be treated as a precious material which is not to be 

 discarded. It is natural to assume that by far the larger 

 part of the dissolved matter yielded by the decomposing 

 red corpuscles finds its way back to the bone marrow to 

 be wrought into new elements. 



White Corpuscles. When one examines blood under 

 the microscope it is possible to detect here and there 



