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How does the Leech feed ? Describe the Alimentary System* 

 The leech is a temporary ectoparasite. It presses its 

 sucker-mouth firmly on the skin, and by means of three 

 chitinous toothed plates, it makes a triradiate cut. The 

 blood is then sucked in by the muscular pharynx, into- 

 which certain gland cells secrete a ferment that prevents, 

 clotting. 



The blood is stored in the crop, the largest part of the 

 3 ut, which has eleven pairs of pockets. The last pair are 

 ^the longest, and lie one on each side of the narrow terminal 

 rectum. Digestion takes place in the very small stomach 

 which is situated between the last pair of storing pockets 

 and the beginning of the rectum. If the crop has been 

 filled, the process of digestion may occupy many months. 



Give a short Account of the Nervous System of Hirudo. 



It consists of a ventral nerve cord with ganglia, and a 

 nerve ring round the pharynx with a double ganglion 

 (the supra-pharyngeal ganglia). The nerve cord is within 

 the ventral sinus. 



How does the Leech breathe ? 

 By the skin, where the blood is oxygenated. 



Describe the Structure of the Nephridium of Hirudo. 



The glandular main portion is U-shaped and twisted ; 

 it consists of cells traversed by a complex system of fine 

 ducts, and its walls are richly supplied with blood capillaries. 

 It ends internally in a " cauliflower lobe " which has 

 minute pores. This lobe is also known as the " testis- 

 lobe," because it is situated in a sinus above the testis. 

 The terminal portion of the nephridium has a muscular 

 and ciliated bladder communicating with the exterior by 

 a short duct. The Leech has seventeen pairs of excretory 

 nephridia. 



Write a short Description of the Reproductive Organs of the 



Leech, 



The Leech is hermaphrodite. The male organs are nine 

 pairs of testes (along the sides of the ventral sinus), com. 



