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Protoplasm,—H. dysenteri@: Shows well-marked distinetion between ecto- and 
endoplasm. This is more marked in the moving organism. WH. coli: Never a 
sharp distinction between ecto- and endoplasm, even when the organism is moving. 
HE. dysenterie:; Ectoplasm much more refractive than endoplasm; the opposite 
is true in ZL. coli. HE, dysenterie: Ectoplasm finely granular; H. coli structureless. 
li, dysenterie: Usually has one or more vacuoles; #. coli rarely shows a vacuole. 
Nucleus.—E, dysenterie: Nucleus usually invisible and when present contains 
but little chromatin and has no marked nuclear membrane. JF. coli: Nucleus 
almost always visible, shows a well-marked, rather thick, nuclear membrane 
which is very refractive to light. Nucleoli and a large amount of chromatin 
present. 
Contained bodies—E. dysenteriw often contains large numbers of red blood 
corpuscles, crystals, bacteria, etc. H. coli rarely contains red blood corpuscles 
(never more than two or three); crystals, bacteria, ete., also diminished. 
Motility.—E. dysenteriv; Motility more marked and definite. LH. coli: Motility 
very sluggish often difficult to distinguish. (This point alone is sufficient to 
distinguish between these organisms in fresh specimens. ) 
STAINED SPECIMENS.—Protoplasm.—H. dysenteriw: Eetoplasm takes much 
deeper stain than endoplasm. #. coli: Endoplasm takes much deeper stain than 
ectoplasm. (This point alone is diagnostic. ) 
Nucleus.—H. dysenteriw: Ectoplasm composed of fine granules, in alveolar 
structure. #H, coli: Ectoplasm structureless. H. dysenteria: Endoplasm shows 
large granules in alveolar structure. 4H, coli: Endoplasm composed of much 
smaller granules. #. dysenteriae: Nucleus stains much less intensely than ZL. coli. 
HB. dysenteriae: Amount of chromtain also much smaller and often no nucleus 
can be demonstrated. 
Reproduction,— Both reproduced by simple fission; also 2. dysenteriv reproduces - 
by process of budding. Portion of nucleus is extended, chromatin is diffused in 
protoplasm, and eventually collects in small clumps around the periphery of the 
organism, These are then given off with portions of protoplasm as young 
amebe, #H. coli reproduces after cyst formation. Eight small amebx are 
formed within the cyst which breaks down and liberates them. 
“These organisms are so easily*distinguished that there should be no difficulty 
in differentiating them by experienced laboratory men.” 
Our own observations have had the advantages accruing from the 
study of cultures of amcebe. These cultures have included stems from 
the dysenteric intestine, from the stools of patients without diarrhoea, and 
from water, vegetables, and other extraneous sources. After careful 
observation of more than one hundred cultures from these different 
sources, and extensive experimentation on animals, together with a study 
of the parasites in stools and tissues, we can not avoid questioning the 
justification for establishing the two species, “H. coli” and “F. histolytica.” 
We do not at all question the multiplicity of both genera and_ species 
of amcebee, both within and without the intestines of men, but it does 
seem as if more work should be done before any classification can be 
substantiated. 
Whatever may be said concerning the general classification, when it 
comes to the establishment of a harmless species, “H. coli,’ and a patho- 
genic one, “EH. histolytica,” the supporting data given are insufficient, as 
will be shown when the pathogenicity of amcebe is discussed. 
