xv, 4 De Leon: Balantidium Haughwouti 399 
In that organism the endoplasm is traversed by a branching and 
ramifying system of excretory canals which unite and discharge 
into a single ciliated efferent duct that opens externally into 
a pore located at the surface of the body near the posterior end. 
It should be noted that in Pycnothrix, and also in Opalma, the 
excretory systems are endoplasmic, a condition differing from 
the ordinary cases in the protozoa where the vacuoles are located 
in the ectoplasm. Both of these forms, however, are nourished 
by the osmotic method, whereas Balantidium haughwouti is 
holozoic. Furthermore, this balantidium possesses definite con- 
tractile vacuoles, which can be seen to pulsate regularly. 
In a rapidly moving animal, possibly caused by the pressure 
resistance of the surrounding medium, the tiny conical papilla 
already mentioned can be seen with considerable distinctness. 
The cytopyge (see fig. 1, e) , as has been said, opens at the tip 
of this papilla and from it can be seen to issue solid substances 
and a mucuslike material. Shrinkage in fixation seems to ob- 
literate this papilla, and in the stained preparations the cytopyge 
only is seen as a minute opening at the posterior extremity. 
This anal pore is apparently the terminal point of the canal 
system mentioned in the preceding paragraph, and it is from 
this that the mucuslike thread is seen to originate. 
This, of course, raises the question as to whether there are 
two distinct systems present; namely, a definite cell anus con- 
nected with a canal system providing for the collection and dis- 
charge of unused substances taken in by the organism, and a 
contractile vacuole system of the conventional type which cares 
solely for the products of catabolism. This is a point I have 
be ; en unable to determine even by feeding carmine granules to 
the animals. It is, however, a condition not unknown in the 
Infusoria. 
The contractile vacuoles are seen as one or two well-defined 
clear spaces just posterior to the meganucleus. Their formation 
is slow and gradual. They are buoyed to and fro by the cyto- 
plasmic movements and, as they enlarge in volume, appear to 
migrate to the extreme periphery, approaching the cuticle sud- 
denly to empty their contents through the cuticle to the exterior. 
The meganucleus is a conspicuous body lying in the endoplasm. 
It can be distinguished from the granules and food vacuoles 
in the living organism by its transparent, homogenous, and 
colorless appearance. It is flexible to a degree, a characteristic 
not uncommon in the Infusoria where nuclei such as are seen in 
the suctorians Acineta and Ephelota show amoeboid contortions. 
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