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THE LIFE HISTORY OF AMOEBAE OF THE UMAX 
TYPE IN THE HUMAN INTESTINE. 
By N. H. SWELLENGREBEL, Ph.D., 
Zoologist of the Colonial Institute, Amsterdam, 
AND RADEN MAS MANGKOE WINOTO, M.B., 
Civil Medical Service, Dutch East India. 
{From the Section of Tropical Hygiene, Colonial Institute, Amsterdam. 
Director: Prof. J. J. van Loghem.) 
(With Plate II, and 1 Text-fig.) 
At the time investigators were trying to cultivate the amoebae of 
the human intestine (Entamoeba coli and E. histolytica), amoebae were 
often encountered in the cultures which were referred to the species 
‘‘'Amoeba Umax,’''’ with many sub-species. Subsequently it was 
found that the cysts of these cultural amoebae are very common and 
that it is possible to cultivate amoebae from nearly every source. 
Consequently it was concluded that these forms do not really live in 
the human intestine but that the cultural amoebae developed from 
cysts, occasionally ingested with food, the cysts not having developed 
in the intestine. This is Walker’s (1911) view, but Chatton and Lalung 
Bonaire (1912) hold that the Umax amoebae (hereafter called Umax) 
can live in the intestine, not only in the form of cysts but also as motile 
amoebae. Cultures made from these stools showed amoebae and 
uninucleate cysts. The latter were not found in the faeces, which 
showed only the motile stages, without however any signs of division. 
The cultures showed this amoeba to be of the common limax-type 
with a vesicular nucleus containing a large karyosome. These observa¬ 
tions are important because they contradict the hypothesis that 
Entamoebae when cultivated show the features of Umax. There is 
