92 C. CLIFFORD DOBELL. 
instance, in Trichomastix lacerte, according to Prowazek 
(39). But really very little information is to be gleaned from 
the literature on the subject. 
(p) The reservoir and contractile vacuole.—Owing 
to the circumstance that the monad is quite motionless during 
the doubling of these structures I have been able to observe 
the process with considerable accuracy. It can be most 
easily described with the aid of a diagram (see text-fig. B). 
Before division the monad is seen to possess one reservoir 
(R.) with a single adjacent pulsating vacuole (cv'). In fig. 2 
the flagellum thas been drawn in, and the cytopharynx has 
disappeared. Later (fig. 3) the two new flagella have made 
Trxt-rFic. B. 
their appearance and a cleft can be seen between them. On 
the left of the reservoir a new contractile vacuole (cv?) has © 
suddenly made its appearance, the old one (cv') remaining in 
its original position on the right. 
The interflagellar cleft gradually extends backwards (figs. 
3 and 4), and as it does so it completely halves the reservoir— 
one half going to each daughter-monad. At this stage the 
new cell-mouths are distinctly visible, lying over the vacuole 
apparatus (fig. 4, and see also Pl. 5, fig. 46). 
During the whole of this process the vacuole (or vacuoles) 
continue to pulsate at a rate of about twice a minute. 
I have described this process in some detail, because so 
little appears to be known about it in most flagellates. 
Division of the contractile vacuole has been described by 
some writers, but I think this is very doubtful. For the 
