Dispensatory of the United States. 163 



The proper preservation of leeches is an object of importance to 

 the practitioner, as they are liable to great and sudden mortality. 

 They are usually kept in jars, in clear water, which should be 

 changed twice or three times a week. The jar must be covered 

 with a linen cloth, and placed in a situation not liable to sudden 

 changes of temperature. They will live a long time, and continue 

 active and healthy, without any other attention than that of frequently 

 changing the water in which they are kept. M. Derheims has pro- 

 posed the following excellent method of preserving them. In the 

 bottom of a large basin, or trough of marble, he places a bed, six 

 or seven inches deep, of a mixture of moss, turf, and fragments of 

 wood. He strews pebbles above, so as to retain them in their place 

 without compressing them too much, or preventing the water from 

 freely penetrating them. At one end of the trough, and about mid- 

 way of its height, is placed a thin slab of marble or earthern ware, 

 pierced with numerous holes, and covered with a bed of moss, which 

 is compressed by a thick layer of pebbles. The reservoir being thus 

 disposed, is half filled with water, so that the moss and pebbles on 

 the shelf shall be kept constantly moist. The basin is protected 

 from the light by a linen cover, stretched over it. By this arrange- 

 ment, the natural habits of the leech are not counteracted. One of 

 these habits, essential to its health, is that of drawing itself through 

 the moss and roots, to clean its body from the slimy coat which 

 forms on its skin, and is a principal cause of its disease and death. 



Medical uses. — Leeches afford the least painful, and in many in- 

 stances the most effectual means, for the local abstraction of blood. 

 They are often applicable to parts which, either from their situation 

 or their great tenderness when inflamed, do not admit of the use of 

 cups ; and in the cases of infants, are, under all circumstances, pre- 

 ferable to this instrument. They are indeed a powerful therapeutic 

 agent, and give to the physician, in many instances, a control over 

 disease which he could obtain in no other way. Their use is in a great 

 measure restricted to the treatment of local inflammations; and, as 

 a general rule, they should not be resorted to until the force of the 

 circulation has been diminished by bleeding from the arm, or in the 

 natural progress of the complaint. 



In applying leeches to the skin, care should be taken to shave off 

 the hair, if there be any, and to have the part well cleansed with 

 soap and water, and afterwards with pure water. If the leech does 

 not bite readily, the skin should be moistened with a little blood, or 



