78 WORMS, ROTIFERS, LEECHES, POLYZOA 



for an animal to have within its muscles at one time, when he 

 proved that i oz. of pig's flesh belonging to part of an infected 

 animal which had been unfortunately eaten, and had produced 

 an epidemic, contained no fewer than 80,000 worms. 



The Miner's Worm (Dochmius (Ancylostomiim) ditodenalis) is a 

 dangerous parasitic Nematode which attacks man, causing great 

 harm by burrowing in the intestinal walls and destroying the 

 capillaries. The fertilised eggs leave the host with the excreta, 

 and in damp earth soon develop into larvae. These eat vora- 

 ciously for a time, undergo several moults, and then pass into a 

 resting stage. They may then be carried by surface water into 

 the drinking supply, and, being swallowed, come to rest in the 

 small intestine of the host. By their presence in large numbers 

 hundreds, and in some cases thousands, existing in the same 

 host they produce profound ansemia, with frequently fatal results. 

 It was this worm which caused serious mortality among the 

 miners employed in the excavation of the St. Gothard Tunnel. 



The Guinea Worm (Dracunculus medinensis) is another Nema- 

 toid worm parasitic in man in the Tropics. The female lives coiled 

 up in the subcutaneous tissues of the host, usually in the legs, 

 producing most painful sores, and may attain to a length of 4 

 metres, though generally it is between 18 and 20 inches. The 

 body of the adult female is completely occupied by a uterus 

 crowded with a great number of eggs and embryos, which can 

 only escape by the actual rupture of the mother's body. This 

 is one of the dangers to be guarded against during the process of 

 extracting the worm from the tumour it has produced, which is 

 accomplished by carefully winding the body of the worm, very 

 slowly, round a piece of stick or a pencil, only an inch or two 

 being withdrawn each day. Should the body, through careless 

 or unskilful handling, be ruptured, the contained embryos will be 

 set free and may result in the death of the host. The embryos, if 

 they can escape into water, enter the body of the so-called water- 

 flea or cyclops, and are likely to be reintroduced into their human 

 host with the drinking of unfiltered water. The "gapes " of fowls 

 and the so-called "grouse disease" are produced by Nematoid 

 worms. To the same group belong the Lung-worms, often fatal to 

 calves and lambs, and the Thread- worm (Oxyuris vermicularis), 

 which is a troublesome and common parasite of children. 



