466 



DiPLdzoA And octoMiTiDM 



In front of the nucleus and closely approximated to the anterior 

 end of the body is a well-defined blepharoplast, which, though 

 typically single, may have a secondary smaller blepharoplast 

 associated with it. No sign of a rhizoplast could be seen. 



From this blepharoplast there arise six anteriorly directed flagella, 

 though occasionally one accidentally appears as though directed 

 backwards. When there are two blepharoplasts, then three flagella 

 arise from each. 



These flagella vary considerably in length, being generally much 

 longer than the body, but it is exceedingly difficult to be certain 

 v/here they end, and in the specimens drawn only such portions as 

 could be clearly seen are portrayed, though in other specimens the 

 length was clearly mu(h greater, in some instances quite three 

 limes the length of the parasite. 



Directed backwards, and also arising from the blepharoplast or 

 llepharoplasts, there are two chromatic lines, which, diverging and 

 running on either side of the nucleus, may or may not converge, 

 but in either case end near the posterior margin of the body in very 

 minute chromatic particles, which are generally very diflicult to 

 see. From each of these chromatic particles there arises a posteriorly 

 directed flagellum. 



The chromatic rods are obviously axostyles, and the little particles 

 in which they end may be termed axoplasts. 



It is not often that the axostyles are seen together, as the parasite 

 usually lies so that only one is visible, while the other is almost 

 invisible; but at times they are seen as described above, or at other 

 times when the parasite has shrunk into a rounded mass they may 

 be observed crossing one another. 



No cytostome has been observed, while the periplast is thin and 

 without markings. 



The cytoplasm is vacuolated with food vacuoles. 



Life-History. — Nothing is known of the life-history. 



Pathogenicity.^ — Believed to cause diarrhoea. 



Genus Giardia Kiinstler, 1882. 



Synonyms.— R. Blanchard, 1888; Dimorphus Grassi, 

 1879, nec Haller, 1878; Megastoma Grassi, 1881, nec de Blainville. 



Definition. — Octomitidse with one antero-mesial pair,' two pairs 

 of mesial and one pair of posterior flagella; nucleus usually double; 

 sucker present. 



Type Species. — Giardia intestinalis (Lambl, 1859). 



Giardia intestinalis (Lambl, 1859). 



Synonyms. — Lamhlia intestinalis Lambl, 1859; Cercomonas intes- 

 tinalis Lambl, 1854; Hexamitus duodenalis Davaine, 1875 ; Dimorphus 

 muris Grassi, 1879; Megastoma entericum Grassi, 1881; Megastoma 

 intestinale Blanchard, 1886; Lamhlia intestinalis Blanchard, 1888. 



This parasite lives in the intestine of different species of the 



