64 
C. U. MARTIN AND MURIEL ROBERTSON. 
arises from a separate granule. Near the origin of the 
flagella is the opening of the well-developed pharynx, which 
is one of the most characteristic features of this genus, and, 
as will be shown later, serves as a control in the case of 
doubtful encysting forms. 
The pharynx is roughly horn-shaped, the narrow portion of 
the horn running back to end in the cytoplasm. The inner 
side of the pharynx, i. e. the side towards which the nucleus 
is applied, projects into the lumen of the pharynx as a well- 
marked rib j the cytoplasm has rather a loosely vacuolar 
appearance, and in active specimens is crammed with large 
food vacuoles containing bacteria. 
The nucleus in the active animal is very characteristic, 
both as regards its appearance and position. It consists of a 
large vacuole containing well-developed chromatic masses, 
but the greater portion of the chromatin is condensed upon 
the nucleus wall. 
The nucleus lies near the anterior pole of the animal, in 
close proximity to the opening of the pharynx, so that in 
the majority of specimens it obscures the origin of the four 
flagella. v 
As we have remarked above, we have not been able to 
obtain nearly as complete a series of divisions in the case of 
Chilomastixas in that of the other flagellates. Still, as will 
be seen from the figures of PI. 10, the main outlines of the 
process are fairly clear. Division in Chilomastix is clearly 
transverse to the longitudinal axis of the animal’s body. 
An early stage is seen in PI. 10, fig. 5. Here the 
blepharoplast complex has already divided, and two basal 
granules, bearing two flagella, have passed to a position near 
theanimal’s posterior pole, where there is already an in-sinking, 
the first sign of the new pharynx. It seems probable that 
the new pharynx arises as a bud from the old one. 
The nucleus has already divided, and it is interesting to 
note that each of the daughter-nuclei appears to contain the 
same number of chromatin masses. 
In the still later stages of division (PI. 10, fig. 6) the new 
