ANGIOLOGY 261 



liquid residue is called serum. Serum is plasma with its modifica- 

 tions as the result of coagulation, and as this latter process is 

 brought about by the production of fibrin, we may say that senirrris- 

 plasma minus fibrin-forming elements. 



The proteids of the serum are serum globulin, serum albumin, 

 and a ferment produced as the result of coagulation. As fibrinogen 

 is used up in the process of coagulation, it is not found in the serum, 

 but there is in the serum a proteid known as fibrino-globulin. This 

 is produced from fibrinogen during the process of fibrin formation. 

 The following tabulation gives a clear idea of the difference between 

 the proteids of plasma and of those of serum : 



Proteids of Plasma Proteids of Serum 



Fibrinogen Serum globulin 



Serum globulin Serum albumin 



Serum albumin Fibrin ferment (nucleoproteid) 



Fibrino-globulin 



Fibrinogen is the percursor of fibrin. 



The fibrin of the blood clot of the bird is soft and very lacerable. 

 The serum is usually yellow. 



THE FATE OF THE ERYTHROCYTE OF THE FOWL 



The power of vascular endothelium to ingest red blood corpuscles 

 has been studied by Keys. 



When bacteria or other minute foreign bodies are injected into 

 the blood stream of pigeons, they are rapidly withdrawn from the 

 circulation into the tissues of the liver and of the spleen. The 

 foreign bodies are noted to be contained within cells of a distinct 

 type, which is found in both liver and spleen. This type of cell 

 contains, in addition to the foreign substances injected, much yellow 

 pigment, and when tested for iron by Pearl's method gives a positive 

 Prussian-blue reaction. 



In such specimens there is a display of contrast to other tissues. 

 There is an extensive content of cells possessing the distinct tone of 

 Prussian-blue iron reaction. These cells are distributed rather 

 evenly throughout both the spleen and the liver, but more numer- 

 ously in the liver. 



In the liver, under low-power magnification, these cells appear as 

 blue patches, sharply differentiated from the red-stained paren- 

 chyma. These cells are larger in their greater diameter than the liver 



