16,1 Haughwout and Horrilleno: Intestinal Parasites 35 
It is suggested that the solution of this question may lead to 
a new line of therapeutic attack in the treatment of entamoe- 
biasis in adults. 
Entamoeba coli . — As has been said, this parasite was found 
in 7 per cent of our cases, appearing for the first time between 
the ages of 2 and 3 years. The infections for the most part 
were rather light and do not seem to merit discussion here. 
’ Endolimax nana . — This parasite likewise yielded 7 per cent 
infections in the series. It appeared in one case between the 
first and second year, but other cases were not encountered 
until the sixth year. 
This parasite vv^as first observed by the senior author in the 
faeces of a colleague- in 1914. At that time he referred it pro- 
visionally to the genus Vahlkampfia and regarded it as a free- 
living species that had strayed from its accustomed path. The 
infection persisted, and the organism was given further study 
and compared with several other amoebae parasitic in lower 
animals, having nuclei of the “limax” type. Before the study was 
completed Wenyon and O’Connor published their description of 
Entamoeba nana, and pressure of other work necessitated the 
abandonment of the study. Since then he has observed this or- 
ganism frequently in the stools of Americans and Europeans, 
but it is only recently that he has begun to find cases among the 
Filipinos. The apparent preference of Endolimax nana for 
white-skinned hosts was very puzzling until it developed that 
there was no descrimination on the part of the organism. 
Dientamoeba fragilis . — This organism, encountered in 3 per 
cent of our cases, did not put in an appearance until the eighth 
year. Once it was associated with Endolimax nana. This par- 
asite was first seen by one of us (F. G. H.) in the fseces of 
an American woman residing in Manila, shortly after Jepps 
and Dobell (33) published their paper on Dientamoeba fragilis. 
So far it has been found in Manila in five cases, one American 
and four Filipinos, two of them being adults. 
Kofoid, Kornhauser, and Place (34) have recently reported 
this amoeba in two cases. One case was that of a soldier on 
overseas service, and the other a soldier on home service in 
the United States. This extends the distribution of the para- 
site from England to the United States and through to the 
Philippine Islands. Jepps and Dobell’s paper suggests that the 
distribution may be even wider than this. Probably Dienta- 
moeba fragilis has been mistaken for Endolimax nana in many 
instances. 
