$3<5 TJTE MEDTCINAL LEECH. 



is generally two or three inches in length. The 

 body is formed with numerous annular wrinkles, 

 which the animal has the power of expanding or 

 contracting at pleasure. The tail ends in a circular 

 muscle or sucker, which, when applied to any sub- 

 stance, readily adheres, by the animal's drawing up 

 the middle, so as to have it pressed firmly down by 

 the external air. By this it fastens itself with ease 

 and security, while it extends the other part of the 

 body in any direction; and it is so firmly fixed that 

 it can move its head about to seek for nourishment, 

 without any danger of being carried away by the 

 strength of the current. When the Leech is de- 

 sirous of moving onward, it extends its body for- 

 ward, fixes its head in the same manner that it did 

 its tail, and then loosens and draws that up, and 

 again fastens it near its head as a fresh point to 

 proceed from. 



The head of the Leech is armed with three teeth 

 of a slightly cartilaginous substance, which are so 

 situated as to converge when the animal bites, and 

 leave a somewhat triangular mark on the skin. 

 These are sufficiently strong to pierce the skin of 

 an ox or a horse. Through the holes it forms with 

 them it sucks the blood : this is done by contract- 

 ing the muscles of the throat so as to make the 

 blood rush through the vacuum above the wound 

 into the stomach, which is a kind of membrana- 

 ceous receptacle divided into twenty-four small cells. 

 Here it sometimes remains for several months almost 

 without coagulating, and affords support to the ani- 

 mal during the whole time. It passes off by trans- 



