WORMS AND CCELENTERATA 277 



membrane is strengthened by the worms themselves, 

 and coloured white by deposits of lime. The animals 

 have now entered on a condition of repose, and will 

 only re-awaken into life when the muscles they reside 

 in reach the stomach of a new animal. When this 

 capsule stage is reached about three months from the 

 first infection the danger is over. But many people 

 die before this through the irritation of the intestines, 

 and especially through the inflammation of the muscles 

 affected. 



When the trichinae enter human beings their career 

 is virtually over, because no one can be infected by 

 eating human flesh. It is otherwise with the animals. 

 Rats are the chief victims of these parasites, as in their 

 case the cycle of migrating and capsulating begins 

 afresh, the dead or diseased rats being eaten by their 

 fellows. This would not affect human beings if the rats 

 did not make their way into pig-styes, where they are 

 eaten by the pigs when they die, or even when alive. 

 Thus the worms capsulated in the rat's flesh pass into 

 the stomach and the muscles of the pig, and may come 

 to infect human beings. 



Among the nematode worms there is a large number 

 of parasites. Most of those in Europe that can infest 

 human beings are of a harmless character. The human 

 maw-worm, the female of which measures up to ten 

 inches, and the much smaller oxyuris (two-fifths of an 

 inch), are common in children. These two species have 

 no temporary host ; their eggs, and often the whole 

 animal, are passed by human beings, and if they find 

 their way into the human intestines once more, they 



