ANIMAL PARASITES 27 



PRACTICAL WORK 



The purpose of this practicum is to become acquainted 

 with the principal tapeworms affecting man and some of the 

 animals with which he is closely associated. Using your study 

 of Tamia pisiformis as a basis, carefully examine such of the 

 following species as are available, making drawings of significant 

 features. 



Taenia solium L., the pork tapeworm of man, develops as a 

 cysticercus or " bladderworm " in the flesh of hogs. The adult 

 worm in man measures 2 to 4 meters or more in length and has 

 300 to 1,000 proglottides. The head bears a short rostellum 

 with a double crown of hooks. The ripe proglottides are usually 

 discharged from the human host in short chains and since the 

 species is a dangerous one it is important to note that the uterus 

 of these ripe segments is characteristically branched in a dendritic 

 (treelike) manner with only 5 to 10 branches on each side. The 

 eggs are globular, about 50^ in diameter, with a thick, radially 

 striated embryophore ("shell"). 



Taenia saginata (Goeze), the beef tapeworm, undergoes its 

 larval stage in beef. It is the commonest of the large tapeworms 

 of man in the United States and in most parts of the world. It 

 may measure 12 meters or more in length and possess as high as 

 2,000 proglottides. The head has four suckers but is unarmed, 

 i.e., it lacks hooks. In the ripe segments the uterine branches 

 are more numerous (15 to 30) than in T. solium and are dichoto- 

 mous. The eggs closely resemble those of T. solium but average 

 slightly larger. 



Compare mature proglottides of T. solium and T. saginata 

 with those of T. pisiformis and carefully compare the uterine 

 branching in the ripe segments of the three species. 



Examine demonstration specimens of the cysts in pork or 

 beef, if available. The characteristics of the heads of the two 

 species may be seen in everted heads of the larvae. 



Hymenolepis diminuta (Rudolphi) is a rat and mouse tape- 

 worm that is also transmissible to man. It is a slender worm 20 

 to 40 cm. in length and 3.5 mm. at its greatest breadth. The 

 head is unarmed and has four suckers. The segments, which 

 may number upwards of 1,000, are very short and have the genital 

 pores all on the same side. In each mature segment there are 

 three large round testes, in transverse order. Between the first 

 and second of these are the paired, branched ovaries and the 



