14 
BULLETIN OP THE BUREAU OF FISHERIES 
sometimes quite prominent, flagellates are often seen which show no trace of them 
even when fixed and stained in the same way (figs. 3 and 5). 
MULTIPLICATION OF FLAGELLATES 
Multiplication takes place by a complicated process of binary fission, which in 
its essentials is very similar to that described by Swezy (1915) in Hexamitus. In 
preparation for division, the organism becomes rounded and the chromatin in the 
karvosomes collects in a number of rounded granules, which are evidently chromo- 
somes (fig. 9). These granules are so small and close together that it is very 
difficult to determine the exact number, but there are probably five or six in each 
nucleus. The differentiated region forming the rudimentary cytostome becomes 
indistinguishable from the rest of the protoplasm, but the clear areas surrounding 
the karyosomes are a prominent feature throughout the process of division. Early 
in the prophase each blepharoplast and axostyle divides into two parts, which quickly 
separate so as to lie on opposite sides of the nucleus (fig. 9). No, paradesmose 
connecting the blepharoplasts, as described by Swezy in Hexamitus, could be dis- 
tinguished. The flagella fail to take part in this division, with the result that one 
of the blepharoplasts has two flagella, the other only one, and one axostyle has 
none. A primitive type of spindle, which extends across the nucleus connecting 
with the blepharoplast centrosomes outside the nuclear membrane, is then formed 
from the plastin of the karyosome (fig. 10). The chromosomes are at first 
grouped at the equator of the spindle, but later become distributed along its entire 
length (fig. 11). At a somewhat later stage the daughter chromosomes become 
grouped at each end of the spindle a short distance from the blepharoplast centro- 
somes (fig. 12). At first interzonal filaments can be plainly seen connecting 
the two groups of chromosomes, but these gradually disappear with the formation 
of the daughter nuclei. The telophase appears strikingly like the prophase, exoept 
that there are two pairs of nuclei instead of one, and, just as in the prophase, each 
karyosome is composed of five to six rounded granules embedded in a homogeneous 
matrix (figs. 14 and 15). All the axostyles now bear flagella, but no new ones 
have yet been developed from the blepharoplasts. Just when these appear has not 
been determined. 
It will be noted that dividing individuals retain their flagella throughout the 
process and for that reason are actively motile. Flagellates in different stages of 
division have often been observed in fresh preparations, swimming about as actively 
as the others, but with considerably more irregularity in their movements. On one 
occasion a rounded individual, which was evidently in the last stages of division, 
was observed to separate in less than 60 seconds into two typical flagellates, which 
swam away in opposite directions. 
It is evident from the foregoing account that fission in this species is essentially 
a longitudinal division very similar to the process described by various authors in 
Hexamitus and Giardia. It should be pointed out, however, that no evidence has 
been found of a multiple division such as has been described in Giardia and Hexam- 
itus, and it is not believed that it occurs in this species. 
