STKUCTUEE OF THE WALL OF THE BLADDER. 509 



The wall of the bladder is quite different, for not only is the 

 cuticular envelope tender and the cells of the subcuticula of a more 

 roundish form, but the musculature in particular is but slightly 

 developed, and is composed of fibres which show by no means such 

 a regular arrangement as in the cephalic appendage. One does 

 indeed find bands of fibres which run from the insertion of the head 

 in a meridional and equatorial direction, but a still greater number, 

 especially deep down, run across one another diagonally. We must 

 further note that the fibres form no closed layer, but leave between 

 them more or less wide meshes, which are filled by the cellular 

 tissue. At the angles of the meshes the fibres are often split, and 

 are united together in a still finer network, which penetrates the 

 whole ground-substance. One even sees muscles in connection with 

 the subcuticula, although it is difficult to get a clear idea of their 

 exact nature. Yet the nature of this connection is an interesting 

 point, since it determines that peculiar tuberculated appearance which 

 even Steinbuch^ emphasised as a characteristic of the bladder-worm 

 of the pig. Somewhat similar elevations (0'05-0'06 mm. broad by 

 0'025 mm. high) are indeed to be found in the bladder-worm of 

 Tcenia saginata, but they are much less high and much less regular. 

 The other bladder-worms show, instead of the tubercles, somewhat 

 regular transverse wrinkles, which are, as one can easily see in 

 longitudinal sections of Cysticercus pisiformis, occasioned by a fan- 

 like distribution of the meridional fibres attached to the subcuticula. 

 Perhaps, too, the thickness an^ rigidity of the cuticle, which is much 

 more marked in the bladder-worm just named and in its allies than 

 in those of the human tape-worms, and especially of Taenia solium, 

 exercises some influence on the nature and appearance of the bladder- 

 wall. We have already mentioned that the vessels of the bladder- 

 wall are, like the muscles, united into a meshwork. We need only 

 add that these meshes arrange themselves at the sides of the head- 

 process in two broad bands, which run from the ends of the bladder 

 towards the middle, and finally pass as longitudinal vessels into the 

 head-process, becoming connected laterally somewhat like a rope- 

 ladder. 



The calcareous corpuscles are distributed singly over the whole 

 wall of the bladder, and are specially abundant in the neighbourhood 

 of the head -process, although never so closely crowded as in the 

 cyHndrical body of the worm. 



Before reaching this stage of development, the Cysticercus cellulosm 

 must have lived about three or four months. This does not mean, 



' Loc. cit., p. 11. "Superficies vesicae externa eminentiis granulosis minutissimis 

 innumerabilibusque obsita est." 



Digitized by Microsoft® 



