THE TAPEWORM LARV^ 195 



B. Larva small. Little or no liquid in 

 caudal vesicle. 



1. Larva firm, terminating in a tail- 

 like process. 



II. Larva without caudal vesicle. 



A. Larva worm-like. Found in muscles 

 of fish. 



Cysticercoid 



(Monocercus Davainece 

 teiragonce, larva of 

 Davainea tetragona) 



Cryptocystis 



(Cryptocystis tricho- 

 dectes, larva of Dipy- 

 lidium caninum) 



Plerocercoid 

 (Larva of 

 Diphyllobothrium 

 latum) 



Cysticercosis (Measles) 



The presence of cysticerci in the connective tissue of muscles and 

 other parts of the animal organism constitutes the condition commonly 

 known as measles (cysticercosis). The disease is mainly of importance 

 from the viewpoint of food sanitation, in view of the fact that measly 

 beef or pork, imperfectly sterilized by cooking, when consumed by man, 

 is hkely to infect him with one or more tapeworms. 



The cysticerci of medical interest are, in their order of frequency: 

 Cysticercus bovis of the ox, the cystic form of Taenia saginata of man, 

 Cysticercus cellulosce of the pig (also of the dog, cat, and occasionally 

 man), the cystic form of Taenia solium of man, and Cysticercus tenuicollis 

 of the sheep (occasionally of the ox and pig), the cystic form of Taenia 

 hydatigena of the dog. 



For the development and structure of the cysticerci the reader is 

 referred to the Life History of the Tsendiise (p. 170). 



Measles of the Ox 



Taenia saginata (T. mediocanellata). Fig. 106. Taeniidse (p. 170). — 

 This species, commonly known as the beef tapeworm, of which Cysti- 

 cercus bovis is the larval form, lives exclusively in the intestine of man. 

 The head (Fig. 109, B) is small, pear-shaped, and has four elHptical 

 suckers which are frequently pigmented. There are no hooks, and in 

 place of the rostellum there is a sucker-like depression. The neck is 



