Resorption of the formed elements 81 



This union with the very small pseudopodia is the first stage in the 

 ingestion of the red corpuscles by the macrophages (Fig. 17). The 

 red corpuscle, seized by amoeboid processes, passes into the interior 

 of the macrophage. This macrophage seldom rests contented with 

 ingesting a single red corpuscle. Usually it devours a large number 

 and sometimes enormous macrophages may be seen filled with a score 

 of red corpuscles. 



If the quantity of goose's blood injected into a guinea-pig is large 

 (5 — 7 c.c), the ingestion of red corpuscles by the macrophages con- [87] 

 tinues for a considerable period — often for three to four days. 

 During the whole of this time a certain number of the red corpuscles 

 remain free in the peritoneal plasma, but, in spite of this prolonged 

 stay, none of them undergo extracellular solution. 



Fig. 17. Macrophage of guinea-pig iu Fig. 18. Macrophage of guinea-pig in 

 process of devouring and digesting red the act of ingesting and digesting red 



blood corpuscles of goose. corpuscles of goose. Intra vitam stain- 



ing with neutral red. 



The red blood corpuscles, anchored by the amoeboid processes of 

 the macrophages, at first present a normal appearance. Later their 

 membrane begins to wrinkle, but as soon as they have passed within 

 the phagocytes the wrinkles disappear and the corpuscles regain their 

 normal aspect. If a little neutral red solution be added to a drop of peri- 

 toneal exudation (Fig. 18) we observe that the nucleus of the ingested 

 red corpuscle and even its contents are stained red, whilst the red cor- 

 puscles adherent to the surface of the phagocytes retain their normal 

 yellow colour. This reaction enables us to see that the red corpuscles 

 are seized by the macrophages whilst still in their normal condition, 

 but that they undergo a change immediately after they have been 

 B. ^ 6 



