136 ANIMAL PARASITES. 



encapsulated by a connective-tissue membrance produced by the inflam- 

 matory reaction of the organ. 



The cyst wall of the parasite is formed of two layers an outer, finely 

 lamellated layer called the cuticula (Fig. 60), and an inner, granular 

 layer, containing muscle fibres and blood-vessels, called the parenchyma- 

 tous layer. Inside of the primary 

 cyst secondary cysts sometimes 

 form, called daughter cysts, and 

 within the latter tertiary cysts, 

 called granddaughter cysts, may de- 

 velop. On the inner surface of the 

 cysts, either primary, secondary, 

 or tertiary, the scolices or heads 

 of the immature worm are formed. 

 These develop in the walls of the 

 pediculated vesicles called brood 

 capsules. The walls of these vesi- 

 cles have a lamellated cuticula and 

 a parenchymatous layer similar to FIG - SI.-SCOLICES OF T^NIA KCHINOCOCCCS, x *>. 

 those of the primary cysts. The In one the Mum * t ^^ in the thersit is 

 scolices, of which there may be 



several in each brood capsule, are similar to the heads of the mature 

 tapeworm. They are about 0.3 mm. in diameter, having a rostellum 

 surrounded by a double row of booklets and four sucking discs (Fig. 

 61). At the posterior end of the scolex is a pedicle by which it is 

 originally attached to the wall of the brood capsule. Little, lamellated 

 concretions of lime salts are often present in the scolex. The anterior 

 portion of the scolex, the rostellum, booklets, and suckers, are often 

 invaginated in the posterior portion. The scolices may be free inside 

 of the brood capsules, or, owing to the rupture of the latter, they may 

 be free in the cavity of the primary cysts. They may die and degen- 

 erate, forming a granular mass in which the booklets may be embedded, 

 or the booklets may be free in the brood capsules or in the primary 

 cysts. Sterile cysts are often found, that 

 is, those in which neither brood capsules 

 nor scolices are developed. 



The cysts contain, in addition to the 

 scolices, a clear, gelatinous fluid. This 

 fluid may become turbid by admixture 

 with disintegrated scolices or fragments 

 of the pareuchymatous layer, or it may 



contain fattv detritus, cholesterin crystals, 



.BOOKLETS FROM SCOLEX OF " . 



T^NIA ECCHIXOCOCCUS. and particles of lime salts. The fluid may 



be partially absorbed, leaving a thick, 



gruinous material within the cysts, which may become calcified or 

 converted into a stony mass. When the scolices are not found entire 

 the diagnosis may be made by the discovery of the separate booklets 



