DIRECTIONS FOR OBTAINING MATERIAL 97 



faeces ; other individuals wander about the body of the host and 

 become encysted in the pleura, liver, and particularly the lungs. 



Next to the intestine, the liver is the visceral organ which is most 

 frequently attacked. Trematodes are found in the gall-ducts and 

 gall-bladder. In North Germany, where cats are very largely infected, 

 the varieties usually met with are Opisthorchis felineus, Metorchis 

 albidus, and M. truncatus ; though these also occur in other localities. 

 In North America, 0. felineus is replaced by a form, 0. pseudofelineus, 

 which closely resembles it, while Clonorchis endemicus is met with 

 in Japan. V. Siebold's assertion that Dicroccelium lanceatum 

 (= Distomum lanceolatum) occurs in the liver of the cat has proved 

 erroneous ; the parasites which he saw were undoubtedly 0. felineus. 

 The true lancet-worm has, however, been observed quite recently in 

 the cat, but its occurrence is extremely rare. 



The gall-bladder should be removed whole, placed in a watch-glass 

 of sufficient size, and then opened along its greatest length. Trema- 

 todes will be seen macroscopically in the gall as it runs out, and their 

 presence may be demonstrated beyond a doubt if the gall is diluted 

 with a little normal saline. It may happen that the secretion is free 

 from parasites ; the liver, however, should be examined in any. case, 

 as these species inhabit the gall-ducts, the larger branches of which 

 should be opened. The entire liver is now cut with a scalpel into 

 slices of about a finger's breadth in thickness ; these should be lightly 

 pressed to force the worms out of the smaller branches of the gall- 

 ducts. They frequently emerge with a jerk on to the cut surface and 

 should be removed with a spatula or paint-brush. The cut surface, 

 upon which there is inevitably a certain amount of blood, is scraped 

 with the back of the scalpel and the material is put into shallow glasses 

 containing normal saline solution. As a certain proportion of the 

 worms are likely to remain in the gall-ducts, the slices of liver should 

 be put on a plate, covered with normal saline solution, and allowed 

 to stand for a time. The worms will be found in the liquid or upon 

 the cut surfaces, or they will emerge if the slices of liver are gently 

 pressed. 



In the case of host-species which harbour parasites in the portal 

 vein, a similar method of examination is followed. The vessel is 

 opened, the blood caught in shallow bowls, and the liver cut into 

 slices. Both blood and the material obtained by scraping are spread 

 in small quantities upon plates, one half of which has been blackened. 

 The material should be thinned with normal saline and the fluid 

 should be slowly moved from side to side during inspection. 



In certain host-species, encysted Helminthes are met with in the 

 liver, the most prevalent being the bladder-worm. They are some- 

 times attached to the surface, sometimes they lie deeper. They may 

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