50 VERMES. 



Order 4. Cesioda. Tape-worms. Elongated endoparasites, without 

 gut or sense-organs, but with an attachment apparatus at the anterior 

 end. Excretory organs consist of longitudinal canals, with branched 

 canalettes. Hermaphrodite (numerous testes, with vas deferens, cirrus, 

 and cirrus-sac. Ovaries, yolk-glands, spermatheca, shell-glands, uterus, 

 and vagina). Numerous sets of reproductive organs usually present, 

 contained in generative " segments " (proglottides) budded off from an 

 anterior head. With advancing ripeness the male organs disappear ; then 

 the female organs with the exception of the exit passages. Two nerve- 

 trunks, united in the head. Development seldom direct or with 

 alternation of generations, mostly with a metamorphosis. The eggs 

 generally reach dung-heaps or water, then enter with the food the 

 stomach of omnivorous or plant-eating animals, where the egg-shells are 

 ruptured ; the freed six- (rarely four-) hooked embryos bore into the 

 blood-vessels, and develop in the liver, lungs, brain, or muscles to encysted 

 measles (bladder- worm, cysticercus, cysticercoid, ccenurus, echinococcus) ; 

 after passive removal into the intestine of a carnivorous, insectivorous, 

 or omnivorous animal, the everted bladder-worm (scolex) fixes itself 

 firmly to the intestinal wall and grows into a jointed form (strobila). 

 Caryophyllseus mutabilis, non-jointed, in the intestine of Cyprinoids ; 

 young form in Tubifex rivulorum. Archigetes Sieboldii, non-jointed, 

 with direct development, in body-cavity of Tubifex rivulorum. Both- 

 riocephalus with two adhesive pits, young form a scolex ; genital open- 

 ings in the middle of the ventral surface of the proglottis. B. latus, 

 24 to 30 feet long ; in Russia, Poland, Switzerland, and S. France. The 

 eggs, enclosed in shells, hatch in water, the ciliated embryo enters a first 

 intermediate host, and with this as a scolex into the intestine of the pike 

 or burbot. B. cordatus, 3 feet long, in the intestines of dog and man 

 in Greenland. Trisenophorus nodulosus in the intestine of the pike, 

 young form in liver of carp. Ligula simplicissima, non-jointed, in 

 the intestine of water-fowls, and the body-cavity of fishes. Tsenia 

 solium, two to three metres long, with four suckers and a double circlet 

 of (26) hooks; in the intestine of man. Young form (measles, Cysti- 

 cercus cellulosse) in the muscles and subcutaneous connective tissue of 

 swine, seldom of deer, dog, and cat, occasionally in muscles, eye, or brain 

 of man (self-infection). T. saginata (mediocanellata), in the intestine 

 of man, without circlet of hooks ; four metres long ; measles in muscles 

 of the ox. T. ccenurus, in intestine of sheep-dog ; young form in brain 

 of one year old sheep (seldom in the body-cavity of rabbit, &c.) as 

 Ccenurus cerebralis, the stagger-worm; (from the walls of the measles 

 numerous tape-worm heads bud out. Alternation of generations). T. 

 echinococcus, in the intestine of the dog, three to four millimetres long, 

 forming but few proglottides. The corresponding bladder-worm with 

 budding secondary and tertiary cysts in the liver and lungs of domestic 

 animals (Echinococcus veterinorum, E. scolicipariens), or of man (E. 

 hominis, E. altricipariens). 



