STRUCTURE AND LIFE-HISTORY OF COPROMONAS SUBTILIS. 87 
the experiments of Saville Kent (24) appeared to have 
definitely proved that food was ingested at this aperture in 
Huglena, the recent work of Wager (52) throws some doubt 
upon the matter again. From Wager’s observations it is 
clear that at least one function of this structure is connected 
with excretion—that is to say, it serves as a duct for the 
reservoir. Khawkine (26) has made the suggestion that 
liquid food enters by the mouth, but the evidence in support 
of this is by no means conclusive. 
In many monads (e. 2. Oikomonas, etc.) food is ingested 
at any point on the surface of the body. This, however, 
never takes place in euglenoids such as Copromonas, which 
possess an external cuticular covering. 
LIFE-CYCLE. 
The life-cycle may conveniently be considered in two 
periods—a period of asexual multiplication, and a period of 
conjugation and encystment. These two periods are not 
sharply separated from one another, but overlap—that is 
to say, in any given culture some of the monads will finish 
conjugation before others begin. 
The first period of the life-cycle is of variable length, and 
is made up of a very variable number of cell generations. It 
is, therefore, impossible to make any definite statement of 
the duration of this period. In cultures made in the manner 
described on p. 77 the following is the course of events fre- 
quently pursued, and may be taken as a fair average. . But it 
must be remembered that it is only an approximation to the 
truth—not an invariable sequence of phenomena. 
Ist day. Culture made; no monads; a few cysts found 
after careful examination. 
2nd ,, No monads. 
3rd_,, No monads. 
Ath ,, <A few very small monads. 
5th ,, A good many monads, many dividing. 
6th ,, Monads in large numbers, actively dividing. 
