VEEMES 151 



their habit of fastening themselves to the skin of man 

 or any of the lower animals and sucking their blood. They 

 are Usually found in moist places only, often being aquatic. 



FIG. 177. Photograph of the medicinal leech. Natural size. 



The medicinal leech (Hirudo medicinalis) was used fifty 

 years ago for blood-letting when the fallacious idea pre- 



Fi. 178. The large water leech just after a full meal. Ventral view showing both 

 suckers, head at the left. Photograph natural size. 



vailed that people could be cured of sickness by letting 

 out the bad blood. After the leech fastens itself to the 

 skin by its suckers the toothed jaws quickly rasp a hole 



