916 
which, under certain circumstances, may be quite decided. This varia- 
tion illustrates the difficulty or impossibility of securing a constant 
environment. Therefore, until the subject is investigated further, the 
size of amcebe can not be used as a diagnostic character of species 
and the value of such determination in differentiating between so-called 
pathogenic and non-pathogenic varieties is of still less importance, as we 
will point out in another part of this paper. 
Color—The shades of amcebe, which vary from greenish to dull 
grayish, have been noticed almost from the time of their discovery. The 
variation has been explained in many ways and has repeatedly been 
pointed out as an aid in the determination of species. 
Schaudinn and his followers have again brought this question into 
prominence in reference to the classification of these protozoa, by regard- 
ing the difference in color as one of the important distinguishing points 
between the harmless and the pathogenic species of amoebae which they 
found in the human intestine. The variation in color in amcebe is very 
noticeable, but we are not prepared to accept such differences as being of 
any value in determining species; rather it is an index of environment. 
In frequent examinations of the stools from a single patient, we have 
often noticed the increased greenish refractiveness taken on by the 
parasites as the character of the stool changed from the watery, diarrhoeal, 
blood-free discharge of the early stages to the dysenteric stool of a more 
established infection. In the bloody, mucous stools the greenish coloration 
of amoebe is often quite pronounced, but as the case progresses favorably 
under treatment, with the disappearance of blood this color is gradually 
lost and during convalescence we may observe ameebe which are dull- 
grayish in color and of an opaque appearancé. Again, in addition to the 
variation in color due to, or intimately associated with the absorption of 
blood serum or other hemoglobin-containing substances by the parasites, 
we have variations which apparently depend upon the presence of bile 
in the environment.. In cases of dysentery, upon the progressive disap- 
pearance of bile from the feces, we have repeatedly noticed the gradual 
change to a dull-grayish color, by amcebe which before that time had 
shown a most marked, greenish refraction. Ameebe seen in liver and 
other abcesses usually conform more closely to the color accredited to 
“HK. coli” than they do to that assigned to “H. histolytica.” Other influ- 
ences may also play a part in this phenomenon observed in amcebe from the 
intestine and other parts of the human body. However, the incontrovert- 
ible arguments against the supposition that certain colors or differences 
in refraction are of diagnostic importance in distinguishing between 
different species of amcebe are found when we work with cultures of 
these parasites. 
Tn cultures, amoebie may be changed from one color to another. These 
colors are as different as any which have been mentioned in the literature, 
and this phenomenon can be repeated almost at will by such simple 
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