332 THE MICROSCOPIST. 



as proglottides. The cellular connective parenchyma in- 

 closes in its peripher} T . especially on the head, small chalky 

 concretions, in all parts the ramifications of a water-vas- 

 cular system, and in the central parts the sexual organs. 

 Each segment has its special male and female organs of 

 generation. 



Human tapeworms exhibit a complicated metamorpho- 

 sis connected with alternate generation. Generally the 

 ova with the proglottides pass from the intestines and 

 are conveyed with food into the stomach of an animal. 

 The embryos become free in the stomach, and by their 

 movable booklets bore their way into the bloodvessels 

 and are deposited in various organs, as the liver, muscles, 

 brain, etc. Here they become encapsulated and grow into 

 larger vesicles, each of which is a cystworm. From its 

 covering one (cysticercus) or several (echinococcus) nodu- 

 lar depressions grow into the interior, on the bottom of 

 which is the armament of the tapeworm's head, in form 

 of suckers and hooks. The transportation into the human 

 stomach is effected by means of food, especially measled 

 meat. The cyst is digested and the head of the tapeworm 

 set free as a Scolex. This enters the small intestine, be- 

 comes fixed, and develops by gradual formation of seg- 

 ments the tapeworm body. 



Family. Tceniadce. Head pear-shaped or conoidal, with 

 four round suckers. A rostellum or wreath of hooks be- 

 tween the suckers or anterior part of head. Proglottides 

 distinctly separate and generally longer than broad. 



A. Vesicular tapeworms, Cysticcz. Head rarely un- 

 armed (T. mediocanellata\ generally w r ith rostellum and 

 hooks. Middle stern of uterus gives off ramifying side- 

 branches. Openings of sexual apparatus on the border, 

 alternate on each side. 



a. Vesicular tapeworms, whose heads are formed in 

 the embryonal state. 



1. Tcenia Solium. Single, or several together in small 



