Aldred Scott Warthin 73 



gland is found, as in the steer and sheep, in which the majority of the 

 cells of the central portion of the gland are mast-cells. 



Eed-blood cell^^ lie free in the meshes of the reticulum. The small 

 blood-vessels and capillaries of the lymphoid tissue are usually filled 

 with red cells and leukocytes, the large mononuclear form appearing 

 to predominate. Throughout the reticulum there is usually present a 

 varying amount of blood pigment, partly free and partly contained 

 within large mononuclear phagocytes. Eed cells in various stages of 

 disintegration are also found in these cells. Scattered areas of a hyaline 

 substance which stain pink with eosin, red with fuchsin, and blue with 

 Mallory's reticulum stain are often found throughout the lymphoid tis- 

 sue, but are most numerous toward the periphery of the gland. Small 

 hyaline, highly refractile spherules of varying size, usually about the 

 diameter of a red-blood cell, are frequently seen in small groups lying 

 free in the reticular meshes and are also found in the mononuclear 

 phagocytes. They stain intensely with eosin and fuchsin, retaining 

 the latter with Mallory's reticulum stain. These hyaline bodies are 

 evidently the products of the destruction of red-blood cells, as all 

 stages of their formation can be found. They may contain iron, 

 especially those found in the phagocytes, the reaction being absent 

 from many of the free bodies. In some cases these spherules can be 

 seen partly extruded from the phagocyte. 



Beticulum. — The reticulum of the lymphoid areas resembles that of 

 ordinary lymphatic glands. That of the blood-sinuses is much more 

 abundant and of a coarser mesh-like structure than that of the lymph- 

 sinuses of lymph glands. It differs from the reticulum of the 

 spleen-pulp in the same respects. It stains blue with Mallory's reti- 

 culum stain, and consists of branching fibres and stellate or spindle- 

 shaped cells arranged in a coarse mesh-work, the surfaces of which are 

 covered with flattened endothelial cells. Small fibrillge of yellow elastic 

 tissue and occasional unstriped muscle-cells may be scattered through 

 it. In its meshes there are found constantly large mononuclear phago- 

 cytes containing disintegrating red cells. These cells are always more 

 abundant in the reticulum of the sinuses than in the lymphoid tissue. 

 Under certain conditions they are so greatly increased in number as 

 to almost entirely fill the spaces of the sinus. Normally their number 

 i^ individual glands varies greatly, suggesting a possible cyclical func- 

 tion of hemolysis. Glands containing many of these cells may be found 

 side by side with others whose reticular spaces contain but few. The 

 same appearances are found in the hemolymph glands of the lower 

 animals, particularly in those of the dog -and rat, Multinuclear giant- 



