LAMBLIA 41 



(b) Lamblia. 



The third variety of Polymastigina found in man, Lamblia 

 intestinalis (Lambl) is, like Trichomonas intestinalis, K. Lckt., an 

 inhabitant of the small intestine, where it attaches itself to the 

 epithelium by means of a sucker-like depression in its broad anterior 

 end. In addition to this characteristic sucker-like depression, the 

 Lamblia are distinguished by their symmetrical bilateral structure ; 

 by the peculiar tapering form assumed by the motile posterior part ; 

 by the possession of four pairs of flagella, of which one pair is placed 

 at the front edge and two pairs at the hinder edge of the sucker-like 

 depression, while the fourth pair proceeds from the posterior tip of the 

 body ; and further, by the possession of two similar and symmetrically 

 situated nuclei, which together have something the appearance of a 

 dumb-bell. Each flagellum is provided with a characteristic basal 

 structure, from which a nbrillum runs to one of the two nuclei. By 

 careful examination, this nbrillum may be seen as a fine dark line in 

 the living organism; in specimens stained with iron-haematoxylin it 

 takes on a still deeper colour. 



FIG. 8. Lamblia intestinalis : full view ; profile view ; dead upon the intestinal 

 epithelium; encysted. (After Grassi and Schewiakoff, from Braun.) 



Forms similar to that parasitic in man and considered by many to 

 be identical with it, are found in the intestine of mice and rabbits. 

 These are useful for purposes of investigation. It should be borne in 

 mind that the parasites are rarely present in the bowel contents ; they 

 must be removed from the intestinal epithelium to which they will be 

 found adhering. 



(c) Costia. 



There is a third species of Polymastigina of which a passing 

 mention must be made. This is Costia necatrix (Henn.). It is ecto- 

 parasitic upon the skin and gills of freshwater fish and may acquire 



