77 
Special medical significance.— The cystic stage of echinococcus 
is found in practically every organ of the human body, but especial ly 
in the liver, lungs, and kidneys. It is more common in females than 
in males, and more common between the ages of 21 and 40 years. 
Fig. 124.— Portion of hog’s liver infested with evhinococcus hydatid. Natural size. (After Stiles, 
1898a, 112, fig. 101.) 
The symptoms are practically those of pressure from a slowly growing 
mass. Treatment is surgical. 
Prevention. — Keep dogs awa} T from slaughterhouses, thus pre- 
venting them from becoming infected with the tapeworm by inges- 
tion of the cystic stage found in food 
animals; avoid undue intimacy with 
dogs, thus preventing infection from 
dogs by infection through contamina- 
tion with the eggs; destroy ownerless 
dogs. 
Modifications in form. — The cys- 
tic stage of Echinococcus assumes va- 
rious modifications, to which different 
names have been given, either by in- 
tentional renaming of forms alread}^ 
known or under the assumption that 
the forms in question represented distinct species. Several names" 
have been proposed as general designations to include all of these 
modifications. 
a General names, including several or all modifications: Echinococcus infusorium 
Leuckart, 1827; Polycepholus volvox Tschudi, 1837; P. echinococcus Tschudi, 1837; ?E. 
variabilis Siebold, 1837, not accessible (see E. variabilis Huxley, 1852); E. polymor- 
phus Diesing, 1850a; E. cysticus Huber, 1891b; E. unilocularis Huber, 1896a. 
Fig. 125.— Portion of the intestine of a dog in- 
fested with the adult Hydatid Tapeworm 
( Echinococcus granulosus). Natural size. 
(After Ostertag, 1895, 430, fig. 99.) 
