304 
DORIS L. MACKINNON. 
division in such forked forms as I have found stained (PL 
18, fig. 11). 
What happens in division is as follows. The spherical 
karyosome elongates, becomes dumbbell-shaped (PI. 18, fig. 
1), and finally divides into two (PL 18, fig. 2). Each 
daughter-karyosome is surrounded by a clear zone, and takes 
over with it a certain number of the supra-nuclear chromatin 
granules (PL 18, fig. 3); the ^roticulum supporting these 
chromatin grains has previously become much fainter, and 
they show a tendency to wander beyond the limits of the 
nuclear membrane. 
One of the daughter-nuclei so formed remains in the original 
position at the extreme anterior end of the body ; the other 
wanders back just below the periplast until it comes to lie at 
the posterior end (PL 18, figs. 4 and 5). Meanwhile the 
body has shown signs of elongation, a constriction appears 
halfway, and the two halves, after hanging together for some 
time, gradually separate (PL 18, figs. 6 and 7). I have not 
been able to find the last stage of separation in the stained 
material, but I saw it once in the living organism. 
The fate of the flagella and the basal granules is rather 
curious. Generally one basal granule and two flagella go 
over with the travelling nucleus ; sometimes a fine fibril is 
seen to extend from the basal granule to the nucleus (PL 
18, fig. 4). In such a case each daughter-nucleus must 
re-grow two flagella ; in this way I explain the occurrence of 
individuals with exceedingly unequal flagella. The sprouting 
of the new flagella is preceded by division of the basal granule 
into two (PL 18, figs. 4 and 5). But sometimes all four 
flagella remain behind with the stationary nucleus (PL 18, 
figs. 8 and 9), while the wandering nucleus moves off with- 
out any, and presumably must re-grow all four when it reaches 
its destination. If the flagella grow out from the basal granules, 
as seems most probable, we should expect that, in this case, 
the wandering nucleus would receive its share of these, but I 
have not been able to observe this. 
The axostyle may persist for some way through the division 
