T^ENIA SOLIUM 



235 



Malformations are not so common as in Tcenia saginatd ; they consist 

 of two or several proglot tides being partly or entirely amalgamated, forma- 

 tion of single club-shaped segments, fenestration on long or short series of 

 segments and so-called double formation, in which the head has six suckers 

 and the segments exhibit a Y-shaped transverse section. The oncospheres 

 occasionally also possess more than six hooklets. Very slender specimens 

 have led to the description of a particular species or variety (T. tenella). 



FIG. 161. Two fairly mature pro- 

 glottides of Tcsnia solium, with sexual 

 organs and excretory vessels. 



Head of T&nia solium. 



In its fully-developed condition Tcenia solium is found exclu- 

 sively in the small intestine of man ; the head is usually attached 

 in the anterior third, and the chain, in numerous convolutions, 

 extends backwards ; a few mature detached proglottides usually 

 lie at the most posterior part, and these are usually evacuated 

 during defalcation. In exceptional cases single proglottides or whole 

 worms may reach contiguous organs if abnormal communications with 

 them exist, thus they may reach the abdominal cavity and the 

 urinary bladder, or they may be found in a s?-called worm abscess 

 of the peritoneum ; occasionally, in vomiting, single segments or 

 several together may be brought up. 



The cyslicercus stage (Cysticercus cellulosce, fig. 136) that gives 

 rise to Tcenia solium lives normally in the intramuscular connective 

 tissue and other organs of the domestic pig, but it is known to 

 exist also in a few other mammals, such as the wild boar, the 



