64 HELMINTHOLOGY 



the form of development at this stage. The cysticercus, or blad- 

 derworm, has a well-developed bladder, in which is found a re- 

 tracted head bearing all the characteristics of the adult tape- 

 worm head. The ccenurus, while inside of a bladder, like the 

 above, develops a number of daughter cysts, with not more than 

 one head in each, which is capable of developing into an adult 

 tapeworm if ingested by a second host. The echinococcus 

 develops a number of daughter cysts, inside of which there* may 

 be a number of heads. The echinococcus is ordinarily much 

 more vesicular in form. 



a. Cysticercus cellulosa is the larva of the pork tapeworm of 

 man. Examine the cysticerci from the heart or voluntary 

 muscles of a pig. Note the size of the object and determine the 

 presence of a head. 



b. Cysticercus tenuicollis is the diving bladderworm of the ox, 

 and the larval form of Tcenia marginata of the dog. It is one 

 of the largest bladderworms, often an inch and a half or more in 

 diameter. The long, slender, invaginated head can be seen 

 through the tissue. Examine some bladderworms from the 

 peritoneum of cattle. 



c. Multiceps midticeps (Ccenurus cerebralis) is a larval tape- 

 worm found in the brain and nerve cord of the sheep, causing 

 the disease known as gid. Examine a specimen of this ccenurus, 

 noting the number of heads and the characteristics of the same. 



d. Echinococcus multilocularis is found in man, cattle and 

 swine, and is the larval form of a tiny tapeworm found in dogs. 

 The echinococcus is found primarily in the liver, but may attack 

 other organs. Here the original cyst develops many daughter 

 cysts, forming an alveolar structure, often of considerable size. 

 Examine a section of human liver affected with echinococcus. 



Drawings of the above types should be made. 



