28 RESEARCH IN PROTOZOOLOGY 



were made to draw morphological distinctions between them and 

 their corresponding types in man. In all, six different species 

 names have been proposed for the amoeba found in monkeys that 

 resembles E. histolytica of man, two for the amoeba resembling 

 E. coll, one for Endolimax, one for lodamooha, two for Tri- 

 chomonas and one for Balantidium. For a summary of intestinal 

 protozoa reported from monkeys see Hegner (1928/?) and Kessel 

 (19280?).^ 



The recent tendency (see Mello, 1923; Kessel, 1926 and 1928^; 

 Dobell, 1928) is to regard most of the intestinal protozoa of mon- 

 keys as being identical with the intestinal protozoa of man. Hegner 

 (1929) has found a number of the intestinal protozoa in wild 

 Macacus monkeys that have been recorded previously from captive 

 monkeys. These claims are based on four main lines of evidence. 



1. Morphological 



With the exception of Mathis and Mercier (1917) and Fox 

 (1923) no observers have attempted to differentiate morphologi- 

 cally between the intestinal amoebae of monkeys and of man. The 

 flagellates and Balantidium have not been studied as thoroughly as 

 the amoebae but no apparent cytological differences have been de- 

 scribed. Hegner and Holmes (1923) and Hegner (1924) men- 

 tioned possible mensural differences between Balantidium, Giardia 

 and Chilomastix in man and monkeys. The Giardia and Chilomas- 

 tix found by Kessel (1928c/) in monkeys, however, compare very 

 favorably with the Giardia and Chilomastix he has found in man 

 and he feels, if size and length to breadth ratio are to be accepted 

 in establishing a biometric standard for species differentiation, that 

 a greater number of cases must be observed both from man and 

 from monkeys before such a criterion can be granted. 



2. Cultural evidence 



The growth and behavior of intestinal protozoa in artificial cul- 

 ture media afford a valuable means of comparing species. Evi- 

 dence to date indicates that the intestinal protozoa of monkeys and 

 of man grow with equal facility and exhibit similar behavior in the 

 same egg-serum medium which is now in general use in culturing 

 intestinal protozoa of man. 



^ Through an error Dobell and Laidlaw ( 1926) are reported to have found 

 lodamoeha in Macacus and to have cultured it in vitro. 



