576 



MARGINATA AND CYSTICERCUS TENUICOLLIS. 



forms, we might now suppose that it had attained its complete deve- 

 lopment. But the investigation of older specimens proves the con- 

 trary. For not only does the bladder continue to grow until it has 

 attained the size of a goose-egg or more, but the head-process and the 

 point of attachment also undergo further modifications. 



The most remarkable is that which has to do with the recepta- 

 culuvn. The posterior end of the latter grows into a solid process, 

 and ultimately forms the above-mentioned ribbon (p. 564), which is to 

 some extent a continuation of the head-process, and hangs down to a 

 variable distance in the interior of the bladder. I find the first 

 trace of this structure in the previously described bladder-worms; 

 sometimes, it is true, only in the form of a flat, hump-like projection, 

 which is situated on the receptaculum (Fig. 311 B, a), or rather it is 

 formed out of it by thickening and proliferation of the tissues. Even 

 later, this ribbon, in its histology, is most nearly related to the re- 

 ceptacle. Like the latter, it consists of connective-tissue, which is 

 penetrated by muscle fibres, and contains, besides a few isolated 

 calcareous corpuscles, numerous granular cells. The muscular fibres 

 run principally in the peripheral parts, while the granular cells are 

 deeper down, and are sometimes grouped together into a distinct axial 

 band. Where the ribbon, as sometimes happens, comes into union 

 with the inner surface of the wall of the bladder, the muscular 

 fibres are observed to pass directly into those 

 of the latter. The posterior end is some- 

 times cleft, and even separated into individual 

 fibres. 



We can only briefly indicate the manifold 

 ways in which this structure has been mis- 

 interpreted both by earlier and later observers. 

 Besides, having been occasionally claimed as an 

 intestinal or sexual organ, it was also (unfor- 

 tunately by myself in 1848) associated with 

 the erroneous theory regarding the dropsical 

 origin of the bladder- worms, and was regarded 

 as the remains of the formerly solid tape-worm 

 body. On the contrary, it appears to be in 

 reality, in physiological as well as in morpho- 

 logical respects, a structure of subordinate 

 importance, and is, in short, only a somewhat 

 unimportant outgrowth of the receptacle a luxurious growth, similar 

 to that which sometimes originates in certain conditions in plants. 



Even before the development of this process, the part of the 

 bladder where the receptacle is situated is generally prolonged into 



FIG. 312. Longitudinal 

 section through the head of 

 an adult Cysticercus tenui- 

 cottis, with ribbon-like ap- 

 pendage on the receptacle 

 (after Moniez). (x 20.) 



