TAENIA 



89 



and also in the common dog-flea (ccrtopsyllus canis) and in the flea of 

 man (pulcx iiTitans). 



Taenia Coenurus (Fig, 45). — This taenia is generally about 40 cm. 

 long, although in rare instances it may be 1 m. It has a small pear- 

 shaped head, with twenty-four to thirty hooks and four sucking disks. 

 The anterior links of the colony are always very short, and those at 

 the extreme end are elongated and narrow, 7 to 13 mm. long and 3 to 

 3.5 wide, white and shaped like a cucumber seed. The uterus has a long 

 central body, wath eighteen to twenty-six side branches. The eggs 

 have a hard shell, elliptical and 30 to 30 mm. diameter with an indurated 

 border. The larval state of this taenia, which is the coenurus cerebralis 

 (bladder worm) , varies in size from a small seed to a 

 large egg, and has a numl^er of nursing or daughter- 

 cysts or bladders on its inner wall. It is generally 

 located in the brain, and in rare instances in the spinal 

 cord. It is seen in all ruminants, especially sheep. 



Taenia Echinococcus (Fig. 46) . — This is the smallest 

 taenia of the dog, most dangerous to man. Its greatest 

 length is 4.4 mm., and it has three and in rare instances 

 four segments. The last segment is the largest and the 

 only one to possess sexual organs. The uterus is large 

 and irregular, without any central border. The head is 

 round and has four sucking bodies and twenty-four to 

 forty-eight small imperfectly developed hooks, arranged 

 in two rows. The eggs are round and slightly elongated, 

 the shell being formed in several layers. The bladder 

 worm is the echinococcus polymorphus: the bladder is echmococcus: a, tape- 



. worm, enlarged twelve 



filled With a nonalbuminous fluid and generally has times; h, cyst con tain- 

 daughter-cysts on the sides. These cysts may assume '^^ ^^°-'^'' '^' ^mature 



. ... head. 



enormous proportions, ranging m size from a pea to a 

 man's head or even larger and on the walls we find numerous ammen 

 heads. There are two varieties of the echinococcus, the distinguish- 

 ing characters being the length of the hooks and the arrangement of 

 the eggs. It is found in the pig, cattle and sheep and very rarely 

 in solipeds and carnivora. In man it is generally found in or attached 

 to the liver or peritoneum, but it has also been found in the lungs, 

 kidneys, spleen, muscular system, pleura, bones and the brain. 

 The following parasites are occasionally found in the dog: 

 Taenia Serialis. — This parasite, about 35 to 75 mm. long, resembles 

 the Tsnia coenurus. The intermediate host of this parasite is found in 

 the ral)l)it. 



Taenia Litterata, pscudo-cucumerina , Taenia lineata. This parasite re- 

 sembles the Taenia cucumerina, is found in the fox, but rarely in the dog. 



Taenia 



