NO. 2131. 



NEMATODE PARASITES OF RODENTS— HALL. 



31 



HEPATICOLA HEPATICA (Bancroft, 1893) Hall, 1916. 



Synonyms. — Trichocephalus hepaticus Bancroft, 1803 ; Trichosoma 

 hepaticum (Bancroft, 1893) Railliet, 1898; TrichosoTnum ? tenuissi- 

 mum Leidy, 1891, not Trichosoma tenia'ssimum Diesing, 1851. 



/Specific diagnosis. — Ilepatlcola (p. 30) : Head 7 to 10 /tin diameter. 

 Mouth minutely papillate. Cuticle delicately striate. Worms 4 to 



5 (10 to 12) cm. long. 



Male 28 /x thick at posterior end. Anterior esophageal portion of 

 body about equal in length to posterior portion. A membranous 

 sheath is prolonged from the posterior extremity. No spicule present. 



Female 100 to 120 ju, thick atthemiddleof the body, and 65 [k thick 

 at the blunt tail. Anterior esophageal portion of body half as long 

 as the posterior portion. Prominent swollen membranous vulva 



6 or 7 mm. from the head. Tail very short, blunt, and conical. 

 Eggs (fig. 35) lemon-shaped, 40 to 52 (/, long and 30 to 



35 ^ thick, with the usual opercular plugs at each 

 end. The outer shell is radially striate; the closely 

 approximated inner shell appears liomogenous. 



Life history. — If the eggs containing embryos are 

 fed to rats, tlie emijryos escape from the shell and 

 make their way to the liver. These embryos are 150 /x 

 long and 7 [x. thick, with one end blunter than the 

 other. At a distance of 5 [jl from the narrow head end 

 the embryo is 3 [x thick; at the same distance from 

 the other it is 5 [j, thick. Two days after feeding such 

 eggs to rats Bancroft was unable to find embryos in 

 the intestine of the rat, and no trace of the worms was 

 found in the liver for two weeks, at the end of which 

 time immature W'Orms were found in the liver. Railliet (1892) 

 found embryos in the intestine and liver at the end of five days. In 

 the liver the w^orms mature and copulate. The subsequent fate of 

 the male is not known. It has only been found by Bancroft in feed- 

 ing experiments, and it seems likely that it dies and disintegrates 

 or passes out. The female deposits large numbers of eggs in the 

 liver and finally dies, in the course of two to three Aveeks, according 

 to Bancroft, the body serving as the container for the eggs not yet 

 passed out. According to Perugia (1893) the Avorms are in the 

 biliary canaliculi, but inasmuch as these long worms are found coiled 

 up in the liver, it appears that they extend through the parenchyma 

 largely without reference to the canaliculi (pi. 1). According to 

 Bancroft the eggs do not pass through the bile duct and into the 

 intestine; Railliet says he has found the eggs in the feces. The 

 presence of so many eggs in the liver, associated wath the death of the 

 female, suggests that the propagation of the worm depends on can- 



FlG ^O.—E. EPATICOLA 



HEPATICA. Egg, 

 Enlarged. After 

 Banceoft, 1893. 



