PROTOZOA AND DISEASE 



within this a hyaline substance, c, in which are contained various 

 cellular forms. 1 A few of the largest of these cellular bodies had 

 giant nuclei which stained well with haematoxylin ; in the majority, 

 however, the central portion did not stain like chromatin, but pre- 



^--''"r --~^ r % 

 V, A |^:^QL 



vx * :\ x K . ^^^ ^-^- : ' . >:^^r 



: 



cc 



- - -"-; 



FIG. 24. CYSTIC DISEASE OF THE URINARY TRACT. 



Another part of the same section, showing six cysts : a, Muscularis mucosae ; 

 at b the contents of the largest cyst are subdividing into amoeboid bodies, 

 which are partly dense and partly reticular in structure. 



1 When I first examined this case in 1892, I took the cyst-contents, both cells 

 and intercellular substance, to be due to either hyaline or colloid degeneration. A 

 more critical examination of the large cells, the intercellular substance, and the 

 amoeba-like subdivisions into which both of these broke up, brought me to a different 

 conclusion, as stated below. This more critical examination was due to my being 

 asked by a society, through the secretary, to furnish them with an illustrated 

 account of the case, and at the same time I was directed to describe the bodies 

 as ' psorosperms.' At that time our knowledge of the protozoa was very limited, 

 and the word ' psorosperm ' was loosely applied to coccidia, myxosporidia, etc. 

 There is now no need to retain it. 



