WATEB-SPIDEES AND WATEK-WOEMS. 279 



their use. Many people who sell Medicinal Leeches crowd 

 them together in a large stone bottle nearly full of water. A 

 cloth is tied tightly over the mouth of the bottle to keep the 

 unhappy captives from climbing out of their prison. They 

 are thus kept in the dark as well as ia an unhealthy con- 

 dition. The water, however, is occasionally changed. Never- 

 theless, it is a cruel and unwise way of keeping Leeches, 

 and no wonder the sellers of them complain that they are 

 delicate animals. 



Those who wish to possess Leeches should place them in a 

 large, well-arranged, and securely-covered aquarium, where they 

 will thrive and be seen to the best advantage. They, of 

 course, must have no companions besides those of their own 



Fig. 151. Medicinal Leech (Hieddo medicinalis). 



species, and even of their size; for not only will they feed 

 upon fish, frogs, and the like, but also, at times, upon one 

 another. 



The Medicinal Leeches, of which there are said to be three 

 species, are the best known. They were formerly frequently 

 used in medicine, but now only rarely. At one time there 

 was such a demand for these creatures that they were with 

 difficulty procured, until some Frenchman started what may 

 be called leech-farming; and his venture was so successful, 

 that leech-breeding became on the Continent quite an industry. 

 The commonest Medicinal Leech {Hirudo mediemalis) (Fig. 

 164) is of a dark green colour, marked with six reddish -yellow 

 bands along the back, and the imder-part of the body is 

 greenish and spotted with black. Leeches are oviparous, and 



