BY T. HARVEY JOHNSTON. 63 



species, from within the sp'eeu of an Ep. norvegicus. In 

 February 1909 a liver from Ej). alexandrinus was found so 

 heavily parasitised that about two-thirds of the entire 

 surface, both upper and lower, were studded with the j'ellow- 

 ish- white tubercles, some in large masses measuring one and 

 a-half inches by an inch on one surface and extending 

 through the liver substance to form an irregular j)atch of 

 nearly an inch and a-half in diameter on the other side. 

 On the main lobe, not a square centimeter of the upper 

 surface in any one place was free from it. Worm tracks 

 and worms were abundant, eggs being present in thousands, 

 all the lobes being heavily infected. In spite of this gross 

 infestation the organ was not enlarged, though its substance 

 was much lighter in colour than normal. 



A good account of the parasite was published by Dr. 

 T. L. Bancroft in 1893, who gave the length of the 

 parent worms as 40 to 50mm. {i.e., 1| to 2 inches). 

 A summary of his description is given by Hall (19166, 

 p. 31) who mentions 4 to 5 inches (10- 12cm.) as the 

 length. Leidy (1890, p. 412) in his account of the 

 worm which he called Tricliosomum tenuissimum n.sp.,* 

 estimated it to be two inches long. Owing to the 

 manner in which the nematode threads itself through 

 the liver, it is difficult to extricate it — hence the doubt 

 regarding its length. 



Railliet (1889. p. 62) gave a summary of the earlier 

 referencesf to the parasite in Europe. Chaussat in 1849 

 thought that the nematode eggs in the rat's liver were 

 Coccidium oviforme. In 1860 Davaine believed them to 

 belong to a Trichosoma and gave measurements, while ♦ 

 Colin in 1862 discovered the worm and definitely jDlaced 

 it in that genus. Railliet found the eggs in a mouse in 1885 



* N(jt Trichosoma tenuissimum Diesing, 1851, from the pigeon and 



other Cohinibidae. 



fThese are quoted from Railliet's paper (1889) — Chaussat, Htematozo- 

 aires du Rat, C.R. Soc. Biol., 1, 1849, p. 22; C. Davaine, Traite des 

 Eatozoaires, Paris, Edit. 1, 1860, p. 261 ; G. Colin, Sur la presence d'un 

 Helminthe dans certains tubercules du foie. Bull Soc. imper. de Med. vet., 

 . (2), 7, 1882, p. 156 ; Kitt, T rioenophorus nodulosus in der Leber einer 

 Ratte. Munchnr. Jahrsb., 1879-1880, p. 28; Railliet, Zool. Medicale et 

 agricole, Paris, 1885, p. 164. 



