284 ANiMAL PARASITES. 



generally found in the soft, yellowish-gray, tender, crumbly, mar- 

 row-like, firm, pulpy, infiltrated, submucous tissues, permeated by 

 coagulated blood or pigment, above which there is a normal, 

 but thickened, mucous membrane, only deficient on particular 

 spots, when the submucous tissue then peels off in small pieces ; 

 or they are placed between the mucous and cellular membranes 

 in the form of a grayish-yellow layer of exudation, like fresh, 

 typhous, Pej^erian flakes. At the base of isolated, very firm 

 and solid excrescences, the section shows a cellular stalk, and a 

 sort of radiating framework, which is only a continuation of the 

 normal submucous tissue. Between these different forms there 

 are all sorts of transitions. The muscular membrane of the 

 bladder is, at the utmost, slightly hypertrophied ; and on one 

 occasion only did the serous membranes and the nearest portions 

 of the parietal lamina of the lining membrane of the abdomen 

 exhibit the same darkly pigmented cock's-comb excrescences. 



In the smooth-edged spaces of these excrescences, sitting in 

 the submucous tissue, formed by the diverticula of its vessels, 

 and only constituting productions of the vessels, Bilharz first 

 found the Distoma, and in the mucus and exudation over these 

 spots their eggs. We may from this conclude that the Distoma 

 congregate there to lay the eggs which are to be passed out. 



Action of the Distoma in the ureters. — Not only the mucous 

 membrane of the bladder, but also that of the ureters, or the 

 latter alone, and in rare exceptional cases even that of the pelvis 

 of the kidney, is attacked by the same process. In the ureters we 

 then see irregular, insulated, grayish-yellow, slightly elevated 

 plates, with a soft, tender, firmly adherent coat, of dark urinary 

 gravel, sandy to the touch. This gravel is nothing but a 

 mixture, in molecular masses, of imbedded eggs of Distoma, 

 either empty or containing embryos, with blood, exudation- 

 corpuscles, and crystals of uric acid. Individual embryos also 

 occur free, but Griesinger only found these in a dead state. 

 In consequence of the thickening of the submucous layer, stric- 

 tures of the ureters, with partial or total dilatations above them, 

 take place, as well as retention of urine and its consequences, 

 especially when hypertrophy of the muscular coat occurs at the 

 same time. The kidneys are generally somewhat swollen and 

 filled with blood, and the mucous membrane of the pelvis of the 

 kidney injected. By long duration of the affection the kidneys 

 are subject to fatty degeneration. Pyelitis, and fan-like dilata- 



