2. Study a mounted specimen and observe : the scolex or head, 

 its shape, size, the number and position of the suckers, the terminal 

 beak or rostellum provided with hooks. Are there any sense organs 

 on the scolex? The proglottides begin by faint constrictions just 

 posterior to the scolex. Observe how they increase in size toward 

 the posterior end of the worm. Along the sides of the body run- 

 ning through the whole series of proglottides, observe a clear tube 

 the main trunk of the water vascular system. Can you find any 

 connections between the trunks on the two sides? Does this trunk 

 reach the scolex? How does it end anteriorly and posteriorly? Can 

 you find any tubules emptying into the main tube ? The sexual open- 

 ing is found near the middle of each proglottis and in this worm 

 (Taenia) on both right and left sides. Trace the ducts which lead 

 from this opening toward the center of the body, and in the older 

 proglottides, notice the uterus, centrally placed and filled with eggs. 

 Each egg consists of a germ cell surrounded by yolk cells and all 

 enclosed in a cell membrane. Only in a very favorable specimen 

 can the glands which form each of these three constituents be seen. 

 Observe the vagina or tube leading from the uterus to the sexual 

 opening. The testes are rounded bodies on each side of the uterus 

 connected by fine tubules which convey the spermatozoa to the vas 

 defcrcus, and thence to the exterior. Study all of the above struct- 

 ures in prepared sections and observe in addition the body wall. 



Make drawings of the entire worm, and of a single ripe proglottis 

 to sJiow all of the organs observed. 



IX. ANGUILLULA ACETI (A Nematode Worm). 



Place a drop of vinegar containing vinegar eels on a slide, cover 

 and examine with the low power of the microscope. Observe :- 



1. Form; Fusiform, anterior end blunter than posterior, body 

 round in cross-section, unsegmented. Four longitudinal lines may 

 be seen on the surface of the body, one dorsal, one ventral, and two 

 lateral. Size ; Female about 2 mm. long ; male about I mm. 



2. Cuticle ; smooth, forming a thick coat over whole body. 



3. Alimentary canal ; mouth terminal in front ; anus on ven- 

 tral side in front of tip of tail; mouth cavity small; oesophagus 1/9 

 the length of body in female, 1/7 in male ; intestine, a straight tube 

 running from oesophagus to anus. 



4. Reproductive system ; this consists of long, blind tubes which 

 lie in the body cavity, and open to the exterior behind the middle of 

 the body in the female, and through the anus in the male ; in the 



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