152 THE FLATWORMS— PLATYHELMINTHES 



is from the dwarf tapeworm of dogs, Echinococcus granulosus, which is 

 found as an adult in the intestine of a dog. It is no more than a third 

 of an inch long, but there may be hundreds present in one dog. It is not 

 difficult for a person to get the eggs when the association between dog 

 and human is too intimate, since dogs often have them on their noses and 

 tongues and seem to have a great desire to lick a person on the mouth. 

 A small child can hardly avoid this show of affection on the part of his 

 pet. Once inside the body the embryo bores through the intestine and 

 finds its way to a suitable spot to encyst. It does not form the small cyst 

 like the pork or beef tapeworms, however, but it produces buds and even- 

 tually a cyst as large as a cocoanut is formed that may have scoleces 

 within numbering in the thousands. They are usually removed surgi- 

 cally. Since a dog very seldom has access to human flesh, it would seem 

 that this is a case where the parasite reached the wrong intermediate 

 host. However, cattle and sheep can also serve as intermediate hosts 

 so the dogs are kept supplied from these sources. 



Classification and Derivation of Scientific Words 



Phylum Platyhelminthes (Gr. platys, flat; helmins, worm; refers to body 

 shape). 

 Class A. Turbellaria (L. turbo, that which spins or whirls around; 

 possibly refers to the fact that these animals when placed in water 

 spin around as they settle down to the bottom). 

 Genus 1. Planaria (L. planaris, flat or plane; refers to body 

 shape). 

 Class B. Trematoda (Gr. trema, hole or sucker; refers to presence 

 of suckers which are on the flukes to attach them to parts of an 

 animal body). 

 Genus 1, Clonorchis (Gr. don, branch; orchis, testes; testes are 

 branched), 

 species a. sinensis (L. Sina, China; locality where this species 

 is found). 

 Class C. Cestoda (Gr. cestos, a girdle). 



Genus 1. Taenia (Gr. taenia, a ribbon; refers to shape). 



species a. solium (L. solium, throne; possibly refers to the ap- 

 pearance of the scolex). 

 species b. saginata (Gr. sagina, fatness; possibly refers to the 

 fattened appearance of the ripe proglottids). 

 Genus 2. Dibothriocephalus (Gr. diphyos, twofold; bothrion, 

 sucker; kepJiale, head; bears two suckers on its head). 



