loS 



THE CESTOIDEA 



likely that 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 polymorphic. 



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, 

 a contractile bladder, and so 

 to the exterior. This is the condition in 

 the larval form, but various modifications 

 occur in this type modifications which 





The excretory system in a +>,,, ,' 

 proglottid of BothriocepMlus tne 7 P en * 

 punctatus, v. Ben (after Frai- 

 pont). a, the largest longi- 

 tudinal ca,nal (= ventral), con- 

 nected to its fellow by several 

 irregularly arranged commis- 



/' from 'the have systematic importance (Fig. VI.). 

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



side, connected together by , . , , i j i i 



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

 Central position; and further, the dorsal 



OCCUr 



This network communicates and the transverse canals are at irregular 



with the dorsal canals at e ; d, , -\ T> .L i AT_- *. i 



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



o?fpr a o r giot ged; /} limits 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 identifies Sommer's " plasmatic canal " as the dorsal excretory canal 

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

 p. 373). 



