THE PERSONAL ENEMIES OF MAN 



343 



d.... 



Pigs and ruminants are also liable to the disease. Gamble says of 

 the bladder- worm stage (in The Cambridge Natural History): — 

 " Echinococcus is most fre- 

 quent in Iceland, where it 

 affects 2 to 3 per cent of the 

 population, and a still larger 

 proportion of sheep; while 

 in Copenhagen, Northern 

 Germany, some districts of 

 Switzerland, and Victoria it 

 is not uncommon, but is fre- 

 quently found during post- 

 mortem examinations when 

 no definite symptoms of its 

 presence had been previously 

 noticed." 



Personal Enemies 



AMONG Round - Worms 



(Nemathelmia). — A number 

 of species of these objection- 

 able forms are found as in- 

 ternal parasites within the 

 bodies of human beings. The Round -Worm {Ascaris htmbri- 

 coides) and Thread- Worm (Oxyti-ris vermicularis) are two of the 

 commonest sorts. Far more dangerous than these is one of the 

 Palisade-Worms {Dochm,ius diwdenalis), 

 which possesses spines in the neigh- 

 bourhood of the mouth, enabling it to 

 burrow in the wall of the small intestine 

 of its host. This worm is the cause 

 of the fatal disease called 

 anaemia ". 



The Guinea- Worm [Filaria medi- 

 nensis\ only too well known in tropical 

 countries, is the cause of serious tumours, 

 especially in the legs. These are caused 



by the female, an elongated (usually 20 to 32 inches) slender 

 creature which lives under the skin of the person affected. 



Trichinosis is an extremely dangerous disorder contracted by 

 eating diseased pork, containing the encapsuled stage of a minute 



Fig. 1240. — Echinococcus Cyst from the Liver of a Cow 



rt, Outer covering of cyst, which has been cut away along b 

 to show the cyst itself [c] ; d, d, d, secondary cysts each of which 

 may produce several tape-worms. Reduced. 



mmers ^ 



Fig. 1 24 1 



-Trichinae encysted in Muscle. 

 Much enlarged. 



