2 2 ANIMAL DRUGS. 



alimentary canal which is provided with a number of 

 side pockets, all pointing forward. Fresh leeches are 

 recognized by their fresh color, their active, elastic 

 movements, and the fact that they do not give up any 

 blood when salt or vinegar is dropped upon the mouth. 



Fresh worms are preferable to those from which the 

 blood has been squeezed, for although the latter will suck 

 blood, they, as a rule, do so less lustily. 



The leeches most commonly employed are : the Gray 

 Leech {Htrudo medicinalis, L.), olivaceous in color, with 

 six reddish longitudinal bands along the back, abdomen 

 spotted with black and showing a blackish line on each 

 side. Its rings are slightly roughened. It inhabits 

 Europe, principally France, Germany, and Hungary. 

 Green Leech (Htrudo offlctnalts, Moq.), greenish, with 

 six dorsal bands similar to those of the former, olivaceous 

 and unspotted abdomen, bordered by a black line. Its 

 rings are very fine. The green leech is found with the 

 gray leech. Dragon Leech (Htrudo troctina, Moq.), 

 bright green on the back, with orange borders; isolated 

 black macules bordered with orange take the place of 

 the longitudinal bands. The abdomen is yellowish green 

 and may or may not be spotted. This leech is an in- 

 habitant of northern Africa. 



There are a number of native species in the United 

 States. 



Collection and Preservation. — The leeches are caught 

 in nets and are best preserved in clear water, at a tem- 

 perature of from io° to 20° C. (50° to 70° F.). The 

 vessel should, be comparatively large and should contain 

 some stones and an oxygen-giving plant. 



Uses. — To relieve congestion and abstract blood locally. 



CANTHARIS. CANTHARIDES. SPANISH FLIES. 



These are the dried bodies of a species of beetle. Can- 

 iharis vesicatoria, L., a member of the MeloidcE or Blister- 



