loS 



THE CESTOIDEA 



FIG. VI. 



likely ih&t the gastric or other digestive juices can pass through 

 the thick cuticle. The lime corpuscles are, moreover, present in 

 Cysticerci, which cannot be affected by gastric juice. Monticelli 

 has found a red pigment associated with the lime corpuscles in 

 Scolex polymorphous. 



The excretory system of the Merozoa (see Pintner, Fraipont) 

 consists typically of a superficial (cortical) network of fine capillaries, 

 into which the flame cells open, and a 

 system of collecting vessels in the medullary 

 region extending throughout the strobila 

 and entering the "scolex." Of these col- 

 lecting vessels there are normally two on 

 each side a dorsal and a ventral situated 

 near the margin of the proglottids. These 

 canals are at first equal, but during growth 

 generally become unequal in diameter, the 

 dorsal being the smaller, resulting in a com- 

 plete disappearance of this one in several 

 Taenia, spp., and in some Tetraphyllidea. 1 

 The two canals of one side pass into one 

 another in the scolex, while at the hinder 

 end of the strobila, i.e. on the last proglottid, 

 kaius they open into a contractile bladder, and so 



g to the ex ? erior ' This is the condition in 



canal <= ventral), con- the larval form, but various modifications 



necteu to its fellow by several A i j j/ . i i_ 



irregularly arranged commis- may OCCUr in this type modifications which 



SLn.7 f th" hav no systematic importance (Fig. VL). 

 single aorsai canal of each In B. latus there are the deep longitudinal 



side, connected together by , . , , f , , 



irregular anastomoses ("island canals, which have a normal, dorsal, and 

 ^& ventral position; and further, the dorsal 

 canals occur only in the young proglottids, 

 Tins network communicates and the transverse canals are at irregular 



with the dorsal canals at e ; d, . i T> j. i. A -L- . l 



foramina secundaria (Wagener) intervals. But whereas this segmental anas- 



o7aprSiot a tid anged; /f it8 tomosis occurs in these Dibothridiata, and 



again in the Taeniidae, it is absent in most 



of the Tetraphyllidea. The two canals of one side, however, 

 always pass into one another in the scolex ; but the transverse 

 cephalic anastomosis may be absent even here, as in most of the 

 Tetraphyllidea (Fig. VII.) ; in others it is represented by a simple 

 transverse canal, as it is also in Tetrarhyncha, whilst in the Taeniidae 

 its place is taken by a circular canal arising, according to Pintner, 

 by the splitting of this, in connection with the formation of a 

 retractile rostellum. 



1 Blochmann identities Sommer's " plasmatic canal " as the dorsal excretory canal 

 of Taenia solium and T. saginta (Centralbl. f. Bakt. v. Parasitenkunde, xii. 1892, 

 p. 373). 



