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 Opalina, 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 fiaughivouti 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 

 been 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. 



167553 6 



