T.ENIASIS 181 



The larva is a ccenurus {MuUiceps serialis; Coenurus serialis) found 

 in the connective tissue of rabbits and other rodents. 



7. Multiceps gaigeri. Taeniidae (p. 170). — This is a species found 

 in India and Ceylon, and described by Hall (Journal of the American 

 Veterinary Medical Association, November, 1916), the larva of which 

 develops in the central nervous system and also in the connective tissues 

 and serous surfaces of ruminants. Thus in its cystic host this species 

 combines the location of M. multiceps and M. serialis, the larva, as in 

 that of the latter, forming an adventitious capsule. 



The material for examination (Bureau of Animal Industry, Hel- 

 minthological Collection) consisted of specimens of tapeworms from 

 the dog and the coenurus from the goat. From his study of these, Hall 

 (1916) regards this species as more closely related to the gid tapeworm, 

 M. multiceps, than to M. serialis. 



8. Echinococcus granulosus (Taenia echinococcus). Fig. 99. 

 Tseniidse (p. 170).— The chain is but 4-6 mm. (3/16-1/4 of an inch) in 

 length, and is composed of a head and three segments. The head is 

 provided with 28-50 small hooks arranged in two rows. The first and 

 second segments from the scolex are incompletely developed, but one 

 segment at a time becoming gravid, — the third, when its length almost 

 reaches that of the rest of the worm. 



Eggs oval, 32-36 microns long, 25-26 microns broad. 



The larva is an echinococcus {Echinococcus granulosus; E. polymor- 

 phus) found in the internal organs, usually the liver and lungs, of rumi- 

 nants and hogs, and also in man (Fig. 117). 



Occurrence. — It follows from their habits that dogs should more 

 frequently harbor intestinal parasites than other domestic animals. 

 Probably over fifty per cent, are infested with varied species, frequently 

 in considerable number. Of these, tapeworms predominate, several 

 species of which often inhabit the intestine of a single individual. 



The intermediate hosts of Dipylidium caninum — ^fleas and lice, the 

 former ubiquitous in relation to canine existence, — would account for 

 the greater frequency of this tapeworm than any other in dogs. Dogs 

 which have access to butchers' offal are, in addition to this species, 

 readUy iofected with Echinococcus granulosus, Taenia hydatigena, and 

 Multiceps multiceps, the cystic forms of which are harbored in organs 

 of the principal meat-food animals, sheep, hogs, and cattle. Hunting 

 dogs and those which roam afield are the most exposed to invasion with 

 Tcenia pisiformis and Multiceps serialis, these having their larval devel- 

 opment in rabbits. In any case, young dogs are more susceptible to 

 intestinal helminthiasis than those which are older. 



Symptoms. — Notwithstanding their frequent presence in large num- 

 bers, tapeworms seem, as a rule, to have little deleterious influence 

 upon the health of dogs. As is true of intestinal worms in general, 



