240 Veterinary Medicine. 



Sexually, each segment is independent being furnished with 

 both male and female organs, opening at one of the borders 

 (Hermaphrodite). The male organs are the first to be developed 

 so that the young segments immediately back of the head are ex- 

 clusively masculine. lyater the female organs appear to ujdergo 

 impregnation and when filled to repletion with ova completely 

 predominate over and overshadow the male organs. The male 

 apparatus consists of a series of pyriforra testicles opening into a 

 sperm duct and penis which may project from the genital orifice. 

 The female apparatus consists in ovaries connected with oviducts, 

 which branch in a variable degree in different species, but in 

 some like the beef tape- worm, come to fill the whole interior of the 

 segments, and virtually obliterate the male organs. 



Two divisions of tape- worms are met with : i. T^nia with a 

 globular or tetragonal head, and 2. BoThriocephalus with flat 

 head perforated at each margin by an opening or bothria. 



Taenia. The taenia passes through five different successive 

 stages of existence in its progress from the ovum to the ripe egg- 

 bearing segment. These are as follows, beginning with the fami- 

 liar tape-worm : 



1. Tape-worm (Strobila). This has the characters already 

 described, and lives in the intestinal canal or some communicating 

 passage like the gall ducts. 



2. Detached Ripe Segment (Proglottis). This is a flat 

 quadrangular white segment found on the newly passed faeces or 

 in their vicinity, and progressing by a worm-like motion. It is 

 literally a bag of ova and when swallowed by a suitable ho.st, or 

 when its ova are taken in with the water or food, it is in the line 



, of further development. If taken in by an unsuitable host, it 

 perishes. 



3. The Ovum set free by the digestion of the proglottis in the 

 stomach of the vertebrate or invertebrate host, soon hatches out 

 an ovoid embryo {^proscolex) furni.shed at one end with six hook- 

 lets for boring purposes. 



4- 4. Proscolex. The 6-hooked embryo hatched from the egg, 

 at once sets about boring into the tissues of its host, and if it has 

 been successful in entering the proper host, and if it should reach 

 the particular organ suited to its development through its next 

 stage, it forms the cystic larva or scolex. 



