4© A Guide to the Zoological Collections in the 



which is slightly drawn out — the protuberance or " rosteh 

 lum" being armed with a ring of booklets — and the 

 equatorial circumference of which is furnished with four 

 large suckers. By careful examination all these details, 

 except only the individual booklets, can be recognized in 

 the exhibited specimens. It is by the booklets and suckers 

 that the parasite adheres to the wall of the alimentary 

 canal of its host. The structure of the segments or 

 "proglottides" cannot be made apparent to the naked 

 eye, and all that can be seen on simple inspection of a 

 large mature proglottis is that it is a flat solid oblong mass 

 with a prominent pore at the middle of one edge : this pore 

 is the genital orifice. 



The proglottis, in fact, is honey-combed with reproduc- 

 tive organs — both elements, male and female, being pre- 

 sent in the same segment — and when it is fully mature it 

 is little more than a packet of impregnated ova. It will be 

 noticed that the pores are not all placed in one series 

 along the same side of the chain of segments, but in two 

 alternating series, on opposite sides. 



A tape-worm goes through a complicated series of me- 

 tamorphoses in the course of its development from the egg. 

 The egg, after liberation from the proglottis, if it finds its 

 way into the stomach of a (vertebrate) " host " does not 

 forthwith develope into a tape-worm, but the resulting 

 embryo, which is furnished with booklets and somewhat 

 resembles in appearance the "head" of the adult tape- 

 worm, bores its way by means of its booklets through the 

 stomach of its host (first or intermediate host) until it falls 

 into one of the blood or lymph vessels, by the stream of 

 which it is carried often to some distant part of the body. 

 Somewhere or other in the tissues of its first or intermediate 

 host it lodges and, becoming encysted, is known as a 

 Cysticercus, or bladder-worm. The bladder-worm may 

 increase in size and may give rise by budding to other 

 generations of bladder-worms, but no further development 

 occurs within the first host. If, however, the first host be 



