PLATE 2 



EXPLANATION OF FIGURES 



3 Capillary network in an adult spleen graft on the fifteenth day of host incuba- 

 tion and on the eighth day of the graft growth. The blood within the capillaries 

 is stagnant and undergoes regressive changes. Macrophages are present and 

 show numerous ingested erythrocytes. 



4 Capillary network in an adult spleen graft on the eighteenth day of host 

 incubation and on the eleventh day of graft growth. The blood within the capil- 

 laries shows further regressive changes. Numerous erythrocytes flow together 

 and are seen in the form of huge structureless blocks, the nuclei disappearing 

 and the cytoplasm gradually losing its hemoglobinic reaction. Macrophages are 

 seen very active in ingesting the disintegrated erythrocytes. Retouched photo- 

 graphs, X 400. 



476 



