937 
similar classes of people in the same country,” we must always consider 
whether a bowel from which the stool to be examined is taken is diseased 
or not. As was stated in our first paper, we can only accept data in this 
connection which have been secured after a careful clinical study sup- 
ported by autopsy records in each case, because it is only after these 
precautions are taken that certainty as to the absolutely healthy condition 
of the bowel can be reached. 
Amoebe may be found in the stools of patients who give no clinical 
evidence of disease, under the following conditions: 
(1) In every case of ameebic infection there is an incubation period, or a 
time intervening between the entrance of the amcbx and the production of lesions, 
during which the organisms may be found in the stools. This incubation period 
may be several months, as was demonstrated in our original communication, and 
it is not improbable that it may sometimes be for years. 
(2) In many cases of genuine amebic infection, after careful treatment. the 
patient apparently and in some instances surely recovers. There is a disappear- 
ance of all clinical symptoms, and an autopsy following death from intercurrent 
disease will establish the fact that a cure has been effected, and yet amoebe have 
been found in the stools for months, or even for a longer time. We have 
repeatedly observed this to be a fact, and R. P. Strong and others in Manila 
have also noticed it. 
(3) Our records show a number of cases in which it is conclusively proved that 
wmeebic infection may occur and yet the patient recover without ever having 
manifested any external symptoms of the disease during life, the fact of ameebic 
infection only being confirmed by autopsies performed when the patients have 
died of other causes. In these cases the organisms would have been found in 
supposedly healthy persons during life. Indeed, the presence of scars and of 
other evidences of a healed, antecedent ameebic ulceration of the colon is quite 
a common post-mortem finding in general autopsy work in the Philippine Islands. 
_ (4) Another class of cases resembling the one just described is that in 
which the infection is slight and the recovery so complete that even a subsequent 
autopsy would reveal nothing abnormal. That this may be the case is proved 
be our experience with the other class which has just been described, in which 
the diagnosis is only possible after an autopsy made possible by death due to 
an intercurrent disease which occurred during the mild, ameebie infection. 
(5) There is the considerable percentage of cases of true ameebiasis in which, 
because of the loéation of the lesions, the extremely chronic character of the 
disease and for other reasons, long periods of time have elapsed during which 
but slight or no clinical manifestations of infection were evident. The absence 
of diarrhea or dysentery in these instances is noticeable. This type of infection 
is so frequent that we shall shortly report fifty cases, with autopsies. 
(6) Finally, it is probably true that in a certain number of cases amebe 
continue to multiply in the human intestine for days, months, or possibly years 
without ever producing ulceration in the bowel. Such cases, if they do exist, are 
not of great frequency and it would be difficult, or impossible, to separate them 
during life from the five groups mentioned above. 
Even if such cases were more frequent and if it were easy to establish their exist- 
ence it would seem much more rational to attribute the failure to infect to the 
"The probable influence of climatic conditions, particularly upon the white 
man in the Tropics, must not here be lost sight of. 
