44 
MALARIA 
tinued development from the asexual forms. 
On the other hand, between the gametocyte 
waves we have observed these forms to dis¬ 
appear entirely and to reappear only after 
a certain number of trophozoite cycles had 
occurred (note charts in article by Boyd 
and Kitchen 1937f). 
Thomson (1914) found that gametocytes 
originated from the asexual forms and 
chiefly in the spleen and bone marrow. 
Apparently he did not observe the spindle- 
shaped forms originally described by Wat¬ 
son (1903). Aragao (1930), studying the 
development of gametocytes in splenic 
puncture smears, noted that the earliest 
male forms tend to be rounded, about two 
microns in diameter and, growing older, 
become ovoid or elliptical in shape, finally 
assuming the adult form. The females, on 
the other hand, are first more band-like, 
stretching across the red cell (Thomson and 
Robertson, 1935, could not confirm this ob¬ 
servation) . As these cells grow they assume 
a spindle shape or in some instances a 
plano-convex form. Later cigar-shaped 
gametocytes may be seen and, finally, the 
mature sausage-like form appears. In the 
earliest stage pigment is not found. 
The present writer observed in peripheral 
blood smears from one patient infected with 
a local strain of P. falciparum, numerous 
spindle-shaped, oval-shaped, and other im¬ 
mature forms (such immature forms were 
not encountered with three other strains 
obtained from different points outside this 
country). This person had not had a severe 
course and these forms appeared on the 
eighth and ninth days after first detection 
of trophozoites. Diagnosis of the sex of 
these parasites could not be made by reason 
of their shape but had to be made on the 
characteristics of the chromatin and pig¬ 
ment. 
While as a rule the, adult male and female 
gametocytes possess morphological charac¬ 
teristics which serve to differentiate them, 
occasionally a little overlapping appears 
and raises doubt. This probably occurs 
chiefly in the case of forms which, while 
they appear to be mature in shape, have 
probably been in the circulation only a 
short while and the diagnostic character¬ 
istics have not yet settled into the individual 
sexual type. 
The characteristics of the two sexes 
briefly are: (a) pigment. In the male the 
pigment is loosely knit, golden brown in 
color, and may be in the form of fine or 
coarse granules, or coarse rods. The female 
pigment is darker, often of a greenish black 
color. The granules tend to be closely 
grouped, even though it is not always in a 
compact mass. Most often it adopts an 
annular arrangement or that of a compact 
mass, neither of which is necessarily sym¬ 
metrical. In both male and female gameto¬ 
cytes the pigment is in close association 
with the nucleus. They occupy a larger 
area in the case of the male, in which the 
position is more frequently essentially in 
the central zone of the parasite, whereas in 
the female they are often situated toward 
one or other pole, (b) chromatin. The 
female chromatin is almost always in a 
compact mass. There may be two such but 
this has not been usual in the writer’s ex¬ 
perience. Thomson (1932) found binucle- 
ated female forms to be common and he 
noted that these were vesicular. We have 
frequently observed vesicular nuclei in the 
female when the nucleus has not been ob¬ 
scured by the pigment mass. In the case of 
a single chromatin body it is usually partly 
or completely surrounded by pigment. The 
color of the chromatin commonly appears a 
little darker in the female, more nearly a 
lavender shade (Giemsa stain). Male chro¬ 
matin is more pinkish and quite diffuse. It 
may be in the form of granules or rods and 
is found intermingled with the pigment and 
usually extending beyond it into an ad¬ 
jacent, almost colorless, semilunar shaped 
area of the cytoplasm. One often notes 
colorless areas between the pigment gran¬ 
ules and it is assumed that these are un¬ 
stained portions of the nucleus, (c) cyto¬ 
plasm. In well stained preparations the 
cytoplasm of the female is usually of a blue 
color the depth of which varies. In the 
male, on the other hand, the color of the 
cytoplasm varies from a pale to a distinct 
pink shade. 
