CESTODES I GENERATIVE ORGANS 



207 



form of cysticercus known as Staphylocystis, and found in the 

 woodlouse (Glomcris). Thus it happens that finally one tape- 

 worm egg produces not one, but numerous tapeworms, for, under 

 favourable conditions, each scolex can form a tapeworm. 



FIG. 135. Section through 

 a piece of a Ccenuris cerebralis, 

 with four cephalic cones in 

 different stages of develop- 

 ment. (From a wax model.) 



FIG. 1 36. Median section 

 through a Cysticercns. with com- 

 plete scolex. (After Leuckart.) 



As the foundation of the scolex there appears a hollow bud, the cephalic 

 cone, usually directed towards the interior of the bladder cavity ; on its internal 

 surface arise the four suckers, and the rostel-lum with the hook appa- 

 ratus is formed in its blind end ; it will thus be ob- 

 served that the head of a Taenia is formed with the 

 parts inside out (fig. 136}. In many cysticerci the head 

 forms at the base of the cephalic cone, and is sub- 

 sequently invaginated. A more or less elongated piece 

 of neck also develops, and even proglottides may appear, 

 as in Cysticercus fasciolaris of the Muridae (appertaining 

 to Tcenia crassicoilis of the cat), a process somewhat 

 analogous to that of Ligula, &c. 



The period that elapses from the time of 

 infection till the Cysticercus is fully developed 

 varies according to the species ; the cysticercus 

 of Tcenia saginata requires twenty-eight weeks, 

 that of Tcenia marginata seven to eight weeks, 

 that of Tcenia solium three to four months, 

 and that of Tcenia echinococcus longer still. 



With one single exception (Archigetes) the 

 cysticerci do not become mature in the place 

 where they developed ; they must be enabled 

 to enter the terminal host, a matter that is 

 usually purely passive, the carriers of the cysticerci or infected parts 

 of animals being usually devoured by other animals. In this manner, 

 for instance, the cysticerci of mice and rats (Cysticercus fasciolaris} 



FIG. 137. Cysticer- 

 cus pisiformis in an 

 evaginated position. 

 18/1. 



