THE LIVER-FLUKES, TAPE-WORMS, ETC. 75 



walls of the alimentary canal and soon develop into the 

 many-jointed adult. Tape-worms cause much trouble, espe- 

 cially to children. 



It is probable that the most common tape-worm affecting 

 man in the United States is one that passes its intermediate 

 stage in cattle. It is known as Tcenia saginata, and is much like 

 T. solium, but the head is depressed instead of being convex 

 at the end, and the hooks, which are conspicuous in T. solium, 

 are wanting in T. saginata. 



It is plain that either one of two things is necessary to 

 prevent infection; all meat must be carefully inspected and 

 any that is "measly" rejected, or it must all 

 be so thoroughly cooked that there will be 

 no chance for any of the encysted forms to 

 remain alive. 



FIG. 21. Head of 

 tape-worm, T & n I a 

 saginata. (Highly 

 mag n i fi ed ; after 

 Wood.) 



FIG. 22. A piece of a muscle of the ox, with 

 three specimens of the tape-worm, Tcenia saginata, 

 in encysted stage. (Natural size; after Osterberg.J 



If a child or an older person becomes infested a physician 

 should be consulted, as many of the vermifuges that are often 

 recommended are unsafe. 



A serious disease of sheep, known as gid, is caused by the 

 cysts, or " bladder- worms, " of a tape-worm, Multiceps multiceps 

 (Ccenurus cerebralis), the adult stage of which is passed in the 

 intestine of the dog. The proglottids pass from the dog in the 

 feces and the eggs are released and splashed on the grass or 

 washed to pools where the sheep drink when the rains come. 

 When the eggs are taken into the stomach of the sheep the 

 embryo is released and makes its way into the blood-vessels and 



