ILLUSTRATIONS 



(From photomicrographs by Charles Martin) 



Plate I. Section of the large intestine of monkey 11. A single Balan- 

 tidium coli suis under the healthy intestinal epithelium. Note 

 the mechanical rupture of the epithelium which the parasite 

 has apparently caused in entering the tissues, the absence 

 of polymorphonuclear leucocytes, and to the extreme left the 

 punctiform haemorrhage with exuding red blood corpuscles. 

 II. Section of the large intestine of monkey 11. Three Balanti- 

 dium coli suis in the deeper part of the mucosa. Note that 

 the balantidia are in the tissues between, and not within, the 

 tubules and the nature of the cellular reactions. 



III. Section of the large intestine of monkey 11. A single Balanti- 



dium coli suis in a blood vessel of the submucosa. 



IV. Section of a mesenteric lymph gland of monkey 31. Several 



Balantidium coli liominis in the edge of the glandular tissue. 

 V. Section of mesenteric lymph gland of monkey 31. A single 

 Balantidium coli hominis in the center of the gland, only a 

 part of which is shown in the figure. Note the cross section 

 of a blood vessel adjacent to the balantidium. 



VI. Section of the large intestine of a man dead from balantidial 



dysentery. An early stage of a balantidial abscess in the 

 submucosa. Note the small cavity filled with balantidia and 

 the infiltration of the surrounding tissues with mononuclear 

 cells. 



VII. Section of the large intestine of a man dead from balantidial 



dysenterj'. A part of an advanced balantidial abscess in the 

 submucosa. The abscess is entirely surrounded by sound 

 tissues. Note the abscess cavity and necrotic material and 

 the balantidia and mononuclear cell infiltration in the sur- 

 rounding tissues. 

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