118 



OTHER FLAGELLATES 



of the Norway rat, house mouse, golden 

 hamster and various wild rodents. It 

 measures 7 to 9 by 2 to 3 (i . 



Wenrich (1933) described Hexamita 

 sp. from the feces of a rhesus monkey. 

 It measured 4 to 6 by 2 to 4 jj, . 



Genus OCTOMIlUi 

 Von Prowazek, 1904 



The body is piriform, with 2 nuclei 

 near the anterior end, and 6 antenior and 

 2 posterior flagella. The body is quite 

 symmetrical, 3 anterior flagella and 1 

 posterior one arising on each side. There 

 are 2 axostyles which originate at the an- 

 terior end and fuse as they pass poster- 

 iorly, emerging as a single central rod 

 from the middle of the posterior end. 

 This genus differs from Hexamita, of 

 which it was formerly considered a syn- 

 onym, in the structure of its axostyles 

 (Gabel, 1954). 



Octomitus pulcher (Becker, 1926) 

 Gabel, 1954 (syn. , O. intestinalis) occurs 

 in the cecum of the Norway rat, house 

 mouse, golden hamster, ground squirrels 

 and other wild rodents. It measures 6 to 

 10 by 3 to 7 /i. 



Genus GIARDIA Kunstler, 1882 



The body is piriform to ellipsoidal, 

 and bilaterally symmetrical. The anterior 

 end is broadly rounded, and the posterior 

 end is drawn out. There is a large suck- 

 ing disc on the ventral side; the dorsal 

 side is convex. There are 2 anterior nu- 

 clei, 2 slender axostyles, 8 flagella in 4 

 pairs, and a pair of darkly staining median 

 bodies. The cysts have 2 or 4 nuclei and 

 a number of fibrillar remnants of the 

 trophozoite organelles. A synonym of this 

 generic name is Lamblia Blanchard, 1888. 



The names given the species of Giardia 

 depend on the authorities concerned. Tra- 

 ditionally, it has been believed that Giardia 

 is highly host-specific, and different names 

 have been given to almost all the forms in 

 different hosts. Thus, if we accept the 



names in Ansari's (1951, 1952) review, 

 the species in cattle is G. bovis, that in 

 goats and sheep G. caprae, that in the dog 

 G. canis, that in the cat G. cali, that in 

 the rabbit G. duodenaiis , that in the guinea 

 pig G. caviae, those in the Norway rat G. 

 muris and G. simoni, and those in the 

 house mouse G. muris a.ndG. microti. 

 However, Filice (1952) was unable to find 

 any morphological difference between the 

 giardias of the laboratory rat and a num- 

 ber of wild rodents, and on reviewing the 

 literature discovered that almost no ac- 

 ceptable cross-transmission studies exist 

 between some species. Altho he did not 

 discuss them all, he appears to have con- 

 cluded that there are only two species of 

 Giardia in mammals, each with a number 

 of races. G. muris occurs in the mouse, 

 rat and hamster, and G. duodenaiis in the 

 rabbit, rat, chinchilla, ground squirrel, 

 deermouse, pocket mouse, man and pre- 

 sumably ox, dog, cat and guinea pig, 

 among others. The essential difference 

 between these two forms is that the median 

 bodies of G. muris are small and rounded 

 while those of G. duodenaiis are long, re- 

 semble somewhat the claw of a claw-ham- 

 mer, and lie approximately transversely 

 across the body. 



In this connection, Hegner's (1930), 

 Armaghan's (1937) and Haiba's (1956) 

 success in infecting laboratory rats with 

 Giardia from man suggests that Filice' s 

 view may eventually prevail. However, 

 careful cross-transmission studies must 

 be carried out before a decision can be 

 made. In the meantime, it is more con- 

 venient to use different specific names for 

 most of the forms from different hosts. 



Associated with this nomenclatorial 

 problem is an important epidemiological 

 one. If it turns out that Giardia can be 

 freely transmitted from one host to an- 

 other, we shall have to revise our ideas 

 about the danger to man of infections in 

 laboratory and domestic animals, and of 

 infections in one domestic animal to others. 

 Here is an area of ignorance which de- 

 serves exploration. 



Giardia has not yet been cultivated in 

 artificial media, a fact which has hampered 



