3 20 



THE ANIMAL PARASITES OF MAN 



increased by the presence in the subcuticular tissue of the worm of 

 reserve food bodies. These bodies are supposed to be of this nature 

 and are spherical, 100 //, to 300 //, in diameter, but also much elongated. 



Calcareous bodies in the Japanese worms were 7*5 //, to 12 p ; in the 

 Florida worms 8*8 ^ to 17*6 //,. 



Mode of Infection. Probably from eating uncooked fish. 



Distribution. Japan, Florida. 



Family. Dipylidiidae, Liihe, 1910. 

 Genus. Dipylidium, R. Lkt., 1863. 



Rostellum retractile, with several rings of alternating hooks ; the latter with a 

 disc-like base, having the shape of the thorns of a rose. Genital pores opposite ; 

 genitalia double. Testes very numerous in the central field ; ovary with two lobes ; 

 the vitellaria, which are smaller, behind them ; the uterus forms a reticulum, in the 

 network of which the testicular vesicles lie ; later on it breaks up into sacs enclosing 

 one or several eggs. The eggs have a double shell. 



Dipylidium caninum, L., 1758. 



Syn. : Tcenia canina, L., 1758, p. p. ; Tcenia 

 moniliformis, Pallas, 1781; Tcenia cucumerina, 

 Bloch, 1782; Tania elliptica, Batsch, 1786; 

 Dipylidium cucumerinum, Lkt., 1863. 



This worm measures 15 to 35 cm. 

 in length and 1*5 to 3 mm. in breadth. 

 The scolex is small, rhomboidal, and 

 has a club-shaped rostellum on which 



m. 



FIG. 217. Dipylidium caninum : on the 

 left, the scolex, neck and the first proglot- 

 tids ; on the right, at the top, a packet of 

 ova ; below, hooks of the rostellum, side 

 and front views ; below, an ovum. Various 

 magnifications. (After Diamare.) 



FIG. 218. Dipylidium caninum ! egg show- 

 ing a, egg-shell (vitelline membrane of Moniez) j 

 b, albuminous coat ; c, internal shell formed of 

 or secreted by an outer layer of blastomeres 

 (Moniez) ; d, hexacanth embryo. (After Benham 

 and Moniez.) 



there are, in three to four rings, forty-eight to sixty hooks resembling 

 rose thorns, the size of those in the foremost being 1 1 //, to 15 //, and those 

 in the hindmost ring 6 //-. The neck is very short, the most anterior 

 segments broad and short, the middle as long as they are broad ; the 



