PLATE 4 



EXPLANATION OF FIGURES 



12 Rabbit, adult. Showing the heavy infiltration of small lymphocytes in 

 a portion of the epithelium covering a lymphatic nodule of Peyer's patch (B). 

 These invading cells occupy spaces in the epithelium, with a varying number of 

 cells in each space. The nuclei of four epithelial cells are indicated. The upper 

 part of the drawing shows a portion of the epithelium of a neighboring villus (C) ; 

 with numerous goblet cells pouring their secretion out upon the free surface (A). 

 Note the absence of goblet cells in the epithelium covering the nodule (B). 

 Wright's stain. X 1400. 



13 Rabbit, adult. Cells from the center of a lymphatic nodule of Peyer's 

 patch following an injection of a 5 per cent aqueous solution of trypan blue. 

 Two acidophilic macrophages which have phagocytized particles of the dye are 

 shown. Two normal lymphoid hemoblasts are also indicated. Stained with 

 safranin. X 1500. 



14 Rabbit, seventeen days. Erythroblastic and granuloblastic cells in the 

 subnodular connective tissue in the region of Peyer's patch. The nuclei of the 

 erythroblasts are pyknotic. Several erythrocytes which have lost their nuclei 

 are seen. Two lymph vessels and one arteriole are present. The erythroblastic 

 cells are in close association with them, while the granuloblastic cells are more 

 distant from them. Stained with eosin-methylene blue. X 1400. 



15 Rabbit, seventeen days. A portion of a large erythropoietic focus in 

 the subnodular connective tissue in the region of Peyer's patch. Several lym- 

 phoid hemoblasts from the adjacent nodule are indicated in the drawing. 

 Stained with eosin-methylene blue. X 1400. 



16 Rabbit, forty-four days. Mononuclear (granuloblasts) and binuclear 

 (granulocytes) eosinophiles in the tunica propria of the intestine in the region 

 of Peyer's patch. Note the rod-like appearance of the granules. Several 

 lymphoid hemoblasts are also present. Hastings-Nochts stain. X 1400. 



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