( 18 )
The differences between the three species of parasite in the above
respects may be tabulated thus :-
Species of
parasite.
Stage found
in the
peripheral
(finger) blood.
Effects of the parasites on
the red blood
corpuscles
containing
them.
Character of
the amoeboid
movements of
the parasite.
Number and
arrangement
of spores.
Charac-
ter of the
sexual forms.
Charac-
ter of the
pigment.
Quartan
All stages
The corpuscle
is practically
unaltered.
generally
oval or more
or less rect-
angular.
Very sluggish
so that the
parasite is
corpusele
and are
arranged
with great
regularity
" like a
daisy."
8-10. They
occupy the
whole of the
Round.
Rarely
seen.
Coarse
black
grains.
Benign
Tertian
All stages
.
The corpuscle
is very much
swollen and
decolourised
Very active
so that the
parasite is
irregular in
shape.
20-23.Not so regularly
arranged.
Round.
Fine
brown
granu-
les or
rods.
Malignant
Tertian.
Only young
"ring" forms
and crescents.
Very rarely
an occasional
segmenting
form.
The corpuscle
is generally
shrunken and
decolourised.
Never swol-
len.

Very active and
with a great
tendency
to assume
the ring
form.
9-10. The
segmenting
form occupies
only about
1/2 - 2/3 of the
red corpuscle.
Crescent-
shaped.
Fine
Brown
granu-
les or
rods.
Hints.
From the point of view of diagnosis by a microscopical examination the
following hints may be useful.
If in a film we find a " crescent," we know at once that we are dealing
with a case of Malignant Tertian fever.
If, at different examination of the same case, we find nothing but small
ring forms, the case is also probably one of Malignant Tertian. Small rings
and crescents are characteristic of Malignant Tertian infections.
If we find a large irregularly shaped parasite in a corpuscle which is
distinctly larger than the surrounding ones, we may be sure that this is a
Benign Tertian parasite.
If we find large regularly oval or rectangular parasites in corpuscles which
are practically unaltered in size and colour, these are probably Quartan parasites.