154 



PRACTICAL PARASITOLOGY 



small glass bowl coated with wax, or on a sheet of cork, and hot 

 sublimate or other fixing fluid should he poured over them. They 

 are finished in the usual manner. The form of the scolex and the 

 shape of the hooks should be carefully noted, as these points have a 

 diagnostic significance. 



There is a variety of 

 Echinococcus, almost in- 

 variably met with in cases 

 of human infection, though 

 rare in cattle, which forms 

 daughter - bladders. The 

 daughter-bladders lie with- 

 m ^ e m ther-bladder, or 

 between it and the sur- 

 rounding cystic wall. They 

 are structurally similar to 

 the mother-bladder, which 

 is the direct outcome of 

 the oncosphere, and they 

 are frequently sterile. A 

 certain proportion form 

 brood-capsules containing 

 scoleces, while others, 

 again, produce a second 

 generation of daughter (or 

 grand-daughter) bladders, 

 similar in construction to 

 themselves. By introduc- 

 ing fresh Echinococcus 

 heads into the pleural or 

 peritoneal cavities, or 

 under the skin, of rabbits, 



it has been shown that the heads develop into bladders, capable of 

 forming brood-capsules containing scoleces a fact as important 

 practically as it is theoretically. 1 



The Cysticercoid stages of Bothriocephalus, known as Pleuracoids, 

 are found in certain fresh- water fish. In Germany, Russia, Italy, &c., 

 these parasites are harboured by varieties of pike, burbot, and perch ; 

 in Switzerland by the Salmonidse ; and in Sweden by the Coregonidge. 

 The Pleuracoids are situated both on and in the viscera, as well as in 

 the muscular structure. When the body-cavity is opened, they appear 

 as white thread-like structures, generally somewhat doubled up, and 



FIG. 75. Echinococcus veterinorum. The cystic 

 membrane surrounding the Echinococcus is opened 

 and turned back in five points. The surface of 

 the parasite is seen with the brood-capsules show- 

 ing through it. (After Leuckart.) Natural size. 



For further information regarding Cysticercoids. see p. 126. 



