PAEENCHYMATOtJS BLADDEK-WOEMS. 



343 



The state of matters in Cysticercus pisiformis further shows us 

 that the excretiou and accumulation of iiuid in the interior of the 

 bladder-worms do not by any means always occur in the same com- 

 plete fashion. I have lately come to know of a number of Cysticerci 

 which had, strictly speaking, no bladder, since the accumulation of 

 water had either never occurred, or only to an extremely small extent. 

 They were all tape-worms without hooks, but I was unfortunately 

 unable to identify them. One of these forms is probably identical 

 with Diesing's Piestocystis variabilis (Fig. 184). I observed it in the 

 lungs of the crow — only once indeed, but in tolerable abundance. 



Fie. 184. — Longitudinal 

 section of an unarmed cystic 

 worm from the lung of the 

 crow (Piestocystis variabilis, 

 Diesing?) (x30.) 



Fig. 185. — Unarmed cystic worm from the 

 body-cavity of Lacerta irivipara (Piestocystis 

 Dithyridium, Diesing). A, with head in- 

 Taginated ; B, with head half extruded ; 

 C, with evaginated head. ( x 30.) 



The bladder has an extremely thick wall, and is filled internally with 

 a mucous tissue which surrounds the narrow bladder-cavity on all 

 sides. Two other allied forms — one from the sub-epidermal tissue of 

 the nightingale, and another (Fig. 185) from the body-cavity of Lacerta 

 vivipara (Piestocystis Dithyridium, Diesing) — are wholly destitute 

 of a bladder-cavity. The interior of the body consists of an interlaced 

 connective substance, which is only so far variable in that its con- 

 sistency decreases towards the centre. "With the loss of the bladder- 

 cavity, most of the characteristic peculiarities of the bladder-worms 

 have been also lost, so that it is hardly possible to distinguish these 

 forms from developed bladder-worms with evaginated heads. In 

 fact, even in spite of the attached caudal bladder, such a form as that 

 represented on Fig. 185, C, looks exactly lilce a young, still unseg- 



mented tape-worm. ,^. .^. ,, ... ^^ 



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