xv, 4 De Leon: Balantidium Haughwouti 397 
fresh specimen, at its junction with the middle third convex 
superiorly, dividing abruptly, the finer granular and the coarsely 
granular cytoplasm lying posterior to it. This constitutes the 
upper limit of the latter. At the extremities of this line may be 
observed, in favorable individuals, a slight constriction or in- 
dentation of the cell wall forming some sort of a neck to the 
individual, a fact which shows that the posterior portion is 
more elastic and expansible laterally than the anterior which, 
as has been previously noted, is capable of comparatively wide 
extension along the 'longitudinal axis. Moreover, this line cor- 
responds, on the ventral surface, to the edge or ventral lip of 
the oral excavation. 
Dorsally, at the most anterior part of this conical structure, 
a row of membranelles is seen constantly in motion. This dorsal 
portion constitutes the dorsal lip of the adoral excavation. It is 
continued laterally on both sides as a thin expansion forming 
the lateral wall through which, under deeper focus, can be seen 
the structure of the oral apparatus. Ventrally, the median 
anterior surface does not reach the most anterior part of the 
animal. Instead it makes an acute dorsoposterior fold to form 
the adoral excavation already mentioned. 
The excavation itself is funnel-shaped. At the bottom of 
it lies the cytostome which leads into a small canal, the cyto- 
pharynx, which, in turn, runs a short course dorsoposteriorly 
to end blindly in the endoplasm in the vicinity of the meganu- 
cleus. The opening between the dorsal and ventral lips measures 
about 11.5 n. The adoral zone is well supplied with membra- 
nelles. The cytopharynx is ciliated. The united action of 
these membranelles and cilia, the movements of which are 
coordinated, serves to conduct the current of food to the endo- 
plasm. The dorsal lip of the adoral excavation is probably 
supplied with myonemes, since the oral area can be much ex- 
panded during active feeding. 
The posterior two-thirds part of the animal is darker and 
coarser in appearance because it contains coarse, dark granules 
having a greenish tinge. In recently well-fed animals these 
granules have a deeper color, more or less bluish green, and the 
granular appearance is overshadowed by a distinctly alveolar 
structure. This alveolar appearance is apparently due to the 
rapid production of a great abundance of food vacuoles, and the 
greenish coloration would seem to be derived from the chromo- 
phyll substance present in the bodies of the vegetable forms of 
