434 J. A. Gilruth and L. B. Bull : 



viscera, with the exception of one mesenteric lymph gland, which 

 showed enlargement and hyperaemia, and on section was found 

 to be mottled with numerous circular greyish areas, pinhead or 

 smaller in diameter, due to proliferation of groups of fixed cells 

 surrounded by a zone of closely packed lymphocytes. 



The small intestinal nodules could be removed from the sub- 

 mucosa in which they were situated with some difficulty. They 

 then presented a translucent cystic appearance, and could be 

 readily squeezed and ruptured between two slides. Examination 

 of the smears made in this fashion demonstrated the presence of 

 spindle-shaped nucleated sporozoites, similar in many respects 

 to the spores of sarcosporidia. 



In sections of the intestines examined under the low power of 

 the microscope, the submucosa is seen to be greatly thickened 

 by spherical masses of new, loose, fibrous tissue enclosing distinct 

 parasitic cysts (Plate LXXII., Figs. 1 and 2), which are so numer- 

 ous that in many parts a single field shows from ten to twelv^e. 

 These cysts, together with the surrounding inflammatory tissue, may 

 be found singly or clustered together, in some cases the mucosa 

 being so implicated as to result in complete atrophy of the 

 muscularis mucosa (Plate LXXIIL, Figs. 3 and 4). The periphery 

 of the new inflammatory tissue is extremely vascular, the capil- 

 laries being greatly distended with blood, and haemorrhages are 

 frequent. In certain regions, especially where the cysts are 

 numerous and close together, there is atrophy of Lieberkiihn's 

 glands, and even complete disappearance of many villi. The 

 mucosa is congested, and there is complete denudation of the 

 surface epithelium, even in the specimens fixed very soon after 

 death of the animal. 



The parasitic cysts vary considerably in size, generally accord- 

 ing to the stage of development : the younger stages observed 

 vary from 0.15 mm. to 0.26 mm.; the intermediate stage from 

 0.3 mm. to 0.5 mm. : and the miature cysts from 0.36 mm. to 

 0.7 mm. in diameter. They are roughly spherical as a rule, but 

 individual specimens in which there is considerable distortion 

 are not uncommon. 



For purposes of description the parasite may be divided into 

 envelope and contents. 



The envelope consists of two zones, an external radiate and 

 fringe-like, and an internal on which the fringes of the outer 



