HOST-PARASITE RELATIONS! INTESTINAL PROTOZOA 



Reptiles 



Giardia varani Lavier, 1923 Varanus 



niloticus 



Amphibia 



Giardia agilis Kunstler, 1882 Tadpole 



Giardia xenopodis Fantham, 1923 Clawed frog 



Fish 



Giardia denticis Fantham, 19 19 Fish (blood) 



Nematode 



Giardia sp. Thomson, 1925 Viannella sp. 



Criteria of species. Some of the giardias from the dif- 

 ferent host Species differ so greatly in morphology that 

 there can be little question regarding their specific rank. 

 The differences between others are slight but constant. 

 Several species listed, such as G. equi and G. boms, have 

 not been described in detail and careful study is neces- 

 sary in order to establish them as distinct. Further study 

 is also required to determine the position of the speci- 

 mens reported from the wild cat, lion, sheep, birds and 

 nematode. One species is known to live about equally 

 well in two hosts, namely, G. miiris, which occurs in both 

 rats and mice. Two of the species, G. muris and G. simoni, 

 live in a single host, Epimys norvegicus. G. simoni is 

 morphologically identical with G. lamblia but is consid- 

 ered a distinct species by Lavier because it is capable 

 of infecting rats, whereas G. lamblia is not. The charac- 

 teristics that have been used by certain investigators in 

 determining the specific rank of the trophozoites of the 

 different species of giardias are length, breadth, ratio 



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