396 
Philippine Journal of Science 
1918 
CYTOLOGY 
The organism is clothed with a fairly thick cuticle — homog- 
enous, transparent, and refractive. Under ordinary conditions 
this cuticle appears to be firm enough to keep the shape of the 
animal constant, and yet under certain circumstances it is seen 
to be flexible enough to allow considerable movement and change 
of shape. The cuticle is traversed by longitudinal lines or stria- 
tions, which on the dorsal surface run from pole to pole ; on the 
ventral surface, anteriorly, they curve dorsad and converge, 
following the depression that marks the position of the adoral 
zone. From these lines spring the comparatively long, slender, 
and delicate cilia, the coordinated fibrillary movements of which 
propel the animal forward. I have been unable to demonstrate 
basal granules at the origin of the cilia. It is not certain that 
these longitudinal lines actually are ridges because in cross sec- 
tions of the organisms the cuticle does not show any raised 
or differentiated areas. It is probable that the lines represent 
the insertion of myonemes, the contractions of which bring 
about the movements of the body. The seeming absence of 
basal granules might be explained on the basis of the supposi- 
tion that kinetic elements, common to both the myonemes and 
the cilia, are contained within the myonemes. 
These lines are plainly visible in the living organism, but are 
hard to distinguish in the fixed and stained specimens. While 
the contractile mechanism of this species is somewhat similar 
to that seen in the closely related genera Stentor and Spiros- 
temum, the body does not show the high degree of contractility 
exhibited by those two nonparasitic forms. 
The medulla con'sists of two distinct cytoplasmic zones ; namely 
a finely granular ectoplasm, and a coarsely granular endoplasm. 
The ectoplasm consists of a narrow strip of clear, almost 
homogenous, refractive, and finely granular cytoplasm around 
the periphery of the cell which, just above the terminus of the 
cytopharynx and at the level of the oral depression, apparently 
expands and becomes continuous with an area of similar struc- 
ture occupying the anterior third of the organism. This is 
probably an optical effect due to the thinness of the body at 
this point and where the endoplasm would appear to be relatively 
scant in quantity. 
This anterior third of the animal is a blunted cone which 
is excavated ventrally. Its base is represented by a line of 
demarcation sharply seen (see fig. 2, b and c ) , especially in the 
