214 PROTOZOAN PARASITISM 



and more delicate than on Balantidium coli. There 

 is only one contractile vacuole, it being situated on 

 one side of the rounded posterior end of the body. 



The macronucleus is rounded instead of kid- 

 ney shaped, measures 6 to 7 microns in diameter, has a 

 definite rim and its chromatin is more loosely ar- 

 ranged in granules through the nuclear network. 

 The micronucleus is about 1 micron in diameter, 

 spherical, and lies in front of the macronucleus. The 

 cyst is usually ovoid. Multiplication is by trans- 

 verse fission. 



Our knowledge of this rare small ciliate is meagre 

 and it is of only scientific interest, if in reality it is a 

 parasitic species. 



NYCTOTHERUS BABA 



As with Balantidium minutum, Nyctotherus baba 

 is more of academic than practical interest, it having 

 been described in only one case, and that by Schaud- 

 inn also, in 1899. This patient suffered from diar- 

 rhoea and it was one of the two that harbored Balan- 

 tidium minutum. 



This organism is beanshaped, measuring 26 to 28 

 by 16 to 18 microns, being even smaller than Balantid- 

 ium minutum. The mouthpiece extends from the 

 anterior end backwards into the body where it enters 

 the endoplasm through a short, oblique, narrow gul- 

 let. The peristome is lined by long delicate cilia, 

 the body covered by short fine processes. As in 



