Introduction to Animal Morphology. 167 



merits. The male organs consist of a testis made up of 

 a cluster of globular, grape-like caeca (Fig. 2 3 , A ^), some- 

 times very numerous, thickest above, and disappearing 

 when the contents are discharged ; the vas-deferens 

 from each testis dilates into a convoluted tube, which 

 at the sexual orifice ends in a thread-like penis, which, 

 when at rest, is coiled in a sheath. The female pos- 

 sesses separate germigenous and vitelligenous glands, 

 an oviduct, uterus, egg-shell gland, bursa-copulatrix 

 (spermatheca), and vagina. These waste after the 

 extrusion of the eggs. The uterus is usually a con- 

 voluted pouch, which, when full of eggs, becomes 

 rosette-shaped, or tree-like. The small oval eggs are 

 yellow or red, with a hard rough shell, and containing 

 many bright yelk granules. These eggs, with their 

 enclosing proglottides, are expelled with the faeces of 

 their host, and the segments crawl slug-like on plants 

 or damp ground, often remaining free for many days. 

 Even after the death of the proglottides, the eggs long 

 retain their vitality. They pass into the stomachs of 

 other animals with the food, the egg-shell softens and 

 falls off, and the liberated embryo (Proscolex) begins 

 to travel through the connective tissues of the body of 

 the new host, or even in its blood-vessels [Leuckart 

 found them in the vena portae). This proscolex is an 

 oval or round clear body, with anteriorly six weak, 

 curved hooks, and a ciliated clothing which soon dis- 

 appears. On reaching a suitable site, the hooks 

 anchor it, and then disappear, and the body becomes 

 stationary. This, acting as a foreign body, causes a 

 local exudation of lymph and development of capil- 

 laries around it, nourishing and encapsulating it. The 

 larva dilates into a sac full of fluid (water with about 



