GENUS: GIARDIA 691 



Schmidt (1920) gave the name Octomitus intestinalis truttce to a form from 

 the intestine and gall bladder of European Salmonidae. 



Alexeiefi (1917, 1917o) placed the forms seen by him (1910, 1912c) in 

 the tortoise and fish in a new genus, Octomastix, as 0. parvus and 

 0. motelloi. Grasse (1924), who has seen the tortoise flagellate in the 

 urinary bladder of Emys orbicularis, accepts this genus, the characters of 

 which differ from those of Hexamita in minor details only. 



Invasion of the Blood by Hexamita. 



Danilewsky (1889) first pointed out that the Hexamita of frogs was 

 able to invade the body cavity and even the blood-stream when the hosts 

 were in poor condition. Plimmer (1914, 1916) observed flagellates of the 

 Hexamita type in blood-films of tortoises (Nicoria 'punctularia and Cistudo 

 Carolina) which had died in the Zoological Gardens. Ponselle (1919) 

 again observed a species of Hexatnita in the blood of the edible frog, Rana 

 esculenta. The infection was readily transmitted to other frogs {R. tem- 

 poraria) by intraperitoneal inoculation of blood. Lavier and Galliard 

 (1925) have also seen the parasite in the blood of frogs, but were unable 

 to infect other frogs by inoculation. 



Genus : Giardia Kunstler, 1882, 



The members of this genus, which are all parasites of vertebrates with 

 the single exception of a form discovered by Thomson, J. G. (1925), in a 

 parasitic nematode {Vianella sp.), are characterized by the possession 

 of two nuclei and a bilaterally symmetrical body, which is rounded 

 anteriorly and tapered posteriorly. There is a dorsal convex surface and 

 a flattened ventral surface, on which is a well-developed sucking disc 

 with a raised edge circular in outline except at its posterior end, where 

 it is indented to form a notch. There are eight flagella, four of which 

 arise from the margin of the sucking disc, two from the posterior end of the 

 body, and two from a median position in the notch of the sucking disc. 

 The axonemes take a complicated course in the body. 



A flagellate of this genus was first seen by Leeuwenhoek, who found 

 himself infected in 1681, as pointed out by Dobell (1920). The human 

 form was again seen by Lambl (1859), who called it Cercomonas intestinalis. 

 Grassi (1879a) established the genus Dicercomonas with two sub-genera, 

 Monomorphus (Hexamita) and Dimorphus (Giardia), but later (1881a) he 

 replaced Dimorphus by Megastoma. He regarded the form in man as 

 identical with others found by him in domestic animals. Blanchard (1888a) 

 proposed the name Lamhlia, which has been in general use for some 

 years. Kunstler (1882), however, had established the genus Giardia for 

 the flagellate seen by him in tadpoles, and there is little doubt that this 

 is the correct generic name for these organisms. 



