STRUCTURE AND LIFE-HISTORY OF COPROMONAS SUBTILIS. 91 
then divides (fig. 44), becoming dumb-bell shaped, and finally 
being constricted into two daughter-granules. From each of 
these a new daughter-flagellum springs up (fig. 45), and on 
reaching the surface becomes visible as the little peg-like 
structure—the shoot which develops into the flagellar stem 
—which I have already described in fig. 4. A corresponding 
stained stage is seen in fig. 46. 
The manner in which flagella multiply has not been made 
out in many organisms. Dallinger and Drysdale (12), James- 
Clark, and others were of opinion that new flagella arose from 
the splitting of the old. On the other hand, Pelletan (in 
Dinobryon) and Klebs (in Huglena [27]) state that the 
new flagella arise by a new growth—one daughter-cell taking 
the old, the other the new. The process seen in Copromonas 
is of interest in connection with the morphology of the basal 
granule (see infra, p. 106). It is probable, however, that 
the flagella divide differently in different species. 
(c) The cytostome.—The doubling of this structure is 
exceedingly difficult to observe. Even in the active adult it 
is often hard to. distinguish, although it becomes more evident 
in monads which have been flattened out. From a number of 
observations on living animals and permanent preparations I 
believe that the cytostomes of the daughter-organisms are 
both new growths, the old cytostome apparatus having 
degenerated. 
Before division the cytostome and cytopharynx are visible 
as a depression from which a dark line extends backwards 
(Pl. 4, fig. 1). As division proceeds this line becomes less 
distinct (figs. 2 and 3), and finally disappears. When the new 
flagellar rudiments first appear they are seen to be growing 
out of little pit-like depressions (see figs. 8 and 9, Pl. 4, and 
fig. 46, Pl. 5), which gradually penetrate the cytoplasm of the 
daughter-cells. These inpittingss are the new cell-mouths and 
their continuations the new cell-gullets. 
As a rule, it appears to be the case among flagellates that 
one of the daughter-monads retains the old cytopharynx, ete. | 
while the other develops a new one. ‘This happens, for 
