164 



PRACTICAL PARASITOLOGY 



If rats or mice are fed with trichinous flesh, sexually mature 

 Trichinae and their progeny will be found in the intestine after the 

 interval of a few days. The wanderings of the parasites, their pene- 

 tration into the muscular structure, the changes to which they give 

 rise, and their subsequent encystment, all furnish interesting material 

 for investigation. 



Of the other Nematodes which, in Central Europe, are parasitic in 

 the intestine of man, the most important are : Trichocephahis trichiurus, 

 which inhabits the caecum and is frequently met with in certain 

 localities, and Ankylostoma duodenale, formerly very prevalent among 

 miners, but now less frequent. Both of these forms (which belong to 



different families, the first being 

 a Trichotrachelide, the second 

 a Strongylide) 'are either of 

 . sufficient transparency in the 

 fresh state to permit of exam- 

 ination whole, or they may be 

 rendered so by suitable treat- 

 ment. Nematodes very rarely 

 occur in the lungs of man, 

 though they are found with 

 considerable frequency in the 

 lungs of the domestic animals 

 and of game. Filaria are equally 

 rare in man in these latitudes, 

 but Filaria equina, found in 

 the body - cavity of the horse, 

 may be used for experimental 

 purposes. Blood filariae should 



FIG. 84.-A piece of trichinous pork, show- be SOU S ht in the bl d f CrOWS 

 ing a very high degree of infection. Magnified. (CoTVUS varieties) . 



The Nematodes of the domes- 

 tic mammals should be examined by the method described. The 

 anatomy of the larger species (Ascaris megalocephala, Cloq., of 

 horses, A. mtulorum, Gze., of calves, A. suum, Gze., of swine) is best 

 studied by means of sections taken from worms which have been 

 well hardened. In the case of the smaller varieties the whole worm, 

 either fresh or after clearing with glycerine, will usually furnish 

 sufficient data. The number of species known to us has become so 

 large that it is not possible to name them, far less describe them, 

 here. It will suffice to give the names of the families to which 

 they belong. To the Ascaridse belongs the genus Oxyuris, examples 

 of which are Oxyuris curvula, Rud., and 0. mastigodes, N., found in 

 the large intestine of the horse. Of the Strongylidse, some inhabit the 



