34 Philippine Journal of Science 1920 
chronic and carrier cases, and it may be that this case was a 
- earrier. Acton states that the crystals may persist in the stools 
for some time following treatment when the encysted amebz 
have disappeared. Inquiry into the history of this case, how- 
ever, failed to develop any evidence of dysentery, which, never- 
theless, does not necessarily establish a clean bill of health for 
the child. 
Matthews and Smith,(40) in their recent paper, have shown 
a rather low incidence of Entameba histolytica infection in five 
hundred forty-eight Liverpool children, only 1.8 per cent of 
whom were infected with the organism. They found 11.1 per 
cent infected with Entameba coli as against 7 per cent in our 
series, and 2.7 per cent Endolimax nana infections as contrasted 
with our 7 per cent. Yorke(56) in a study of autochthonous 
entameebic infections in England and Wales, examined the stools 
of two hundred forty-six children under 12 years of age. Cysts 
of Entameba histolytica were found in only 0.8 per cent, and 
eysts of EH. coli in 10 per cent of the subjects. Out of fifty cases 
of colitis of various types found by Mendoza-Guazon(43) in her 
post-mortem studies of one thousand Filipino children under 5 
years of age, only one was of the ameebic type. 
Recently the incidence of bacillary dysentery in Manila has 
considerably overshadowed entameebiasis as judged by the 
cases that have come under our observation; nevertheless, en- 
tameebiasis is.of frequent occurrence among adults of all races, 
and there is no reasonable doubt that the opportunities for in- 
fection with this organism are as good in the case of children 
as they are with adults. There would seem to be ground for 
the belief that the obligatory tissue parasites among the pro- 
tozoa, such as Entameeba histolytica and Balantidium coli, for 
some reason or other, find the conditions in the juvenile intes- 
tinal tract unsuitable and rarely succeed in establishing them- 
selves there. This is a matter that we believe should be given 
the most careful study—first of all to determine if such is ac- 
tually the case and, if so, why. We hesitate to believe that the 
intestinal mucosa of the child affords a more effective mechan- 
ical barrier than that of the adult. It certainly does not seem 
to in the case of the helminths. We venture to suggest that the 
key may be found in the physiology of the child—possibly in 
the secretion of some endocrinal gland that functions with 
greater activity in childhood than it does after adolescence and 
which may, in some way, exert an inhibitory influence on the 
growth and development of certain tissue-dwelling organisms. 
