INTERNAL PARASITES OR WORMS. 



349 



The following are found in the dog: Tcenia mar- 

 gin-Ota^ T. cucumerina y T. ser- 

 rata, T. eehinococcus, T. so- 

 lium, and BoihriocepJialus la- 

 tus, the last two being common 

 to man and the dog. 



The first three are the most 

 common : T. marginata, the 

 intermediate host of w r hich is 

 the sheep, may attain a length 

 of eight to ten feet ; T. cucu- 

 merina, the most common, ten 

 to twenty inches in length, with 

 a very small head, the segments 

 getting very gradually larger 

 from before backward ; T. ser- 

 rata, intermediate host the hare 

 and rabbit, twenty to forty 

 inches in length. 



To illustrate how tape- worm 

 is propagated and how one ani- 

 mal may prove a source of dis- 

 ease to many, we may mention 

 that a larval or immature form 

 (Ccenurus cerebralis) of a tape- 

 worm exists in the sheep's 

 brain. If this be taken into 



the dog's Stomach it develops 



into a mature tape-worm, the 



eggS Of Which, if Swallowed by 

 . -, -, -, . -. . 



the sheep in drinking-water, 



FIG. 35.-T^NiA SOLIUM (STONE- 



c, generative oi'iflce ; ?, water vascu- 

 lar canals ; g, ovarian duct ; ft, 

 ovarian receptacle ; t, branched 



