356 



SANITARY ENTOMOLOGY 



the segments, the oncospheres, are released by the disintegration and are 

 then ingested by the flea larva or the louse. Sonsino contended that the 

 adult flea could not ingest the egg of this worm and Joycux (1916) has 

 demonstrated this fact. He was able to demonstrate that the larvae can 

 and do ingest the egg easily. The embryos when they reach the intestine 

 escape from their envelopes, the oncospheres, and penetrate into the gen- 

 eral cavity. They are imbedded in the adipose tissues and are very dif- 

 ficult to demonstrate. Here they remain during the metamorphosis. 

 When the adult flea is formed the hexacanth immediately begins to de- 

 velop, even before its host begins to feed. On the second and third days 



Development 

 Cysticercoid 



Developmemt of Tape Worm 



LIFE CYCLE OFDIPYLIDIUM CANINUM. 



The Dog I ape. vvorm. 

 Host I Fleas (Ctenocephalus oanis, C felis, 



PuLEX IBHITANSJ. 



HostH. Dog (Canis familiaris). 

 Cat ^Felis catus). 

 Jackal (Cams aukevsY 



Fig. 63. (Pierce.) 



it is enlarged and the primitive lacuna begins to form. From this point 

 it develops into the cysticercoid. The dog or cat becomes infested by 

 biting or licking up the infected fleas or lice on its body. The flea can 

 spread the infection to human beings that accidentally swallow the in- 

 sects. Possibly in case of children, infection takes place by kissing pets 

 or by pets stealing a drink from a bowl, the contents of which are after- 

 wards given to children. 



Platyhelmia: Cestoidea: CyclophUlidea: Hymenolepididae 



Hymenolepis diminuta (Rudolphi), the YELLOW-SPOTTED TAPE- 

 WORM of the rat, may pass its intermediate stage in larv^ae of a number 

 of insects of diff'erent orders. Nicoll and Minchin found the cysticercoid 



