696 



Balantidium Coli 



There are two nuclei. The larger, or macronucleus, is bean-shaped, kidney- 

 shaped, or, more rarely, oval. The smaller, the micronucleus, is sphericaL 

 There is no digestive tube; the nutritious particles are directly in the endosarc, in 

 which they are digested, any residuum being extruded from the anus. 



Motility. — The organism is actively motile, swimming rapidly at a steady pace 

 or darting here and there. 



Staining. — The organism can be most easily and satisfactorily studied whil^ 

 alive. To stain it a drop of the fluid containing the balantidia is spread upon a 

 slide and permitted to dry. Just before the moisture disappears from the film, 

 methyl alcohol may be poured upon it to kill and fix the organisms. The staining 

 may then be performed with Giemsa's polychrome methylene-blue or iron-hema- 

 toxylon. The cilia usually do not show. 



Reproduction. — This commonly takes place by karyokinesis, followed by trans- 

 verse division, and in cases of experimental infection so rapidly that the organ- 



Fig. 273. — Reproduction of Balantidium coli: 1-5, Asexual reproduction by 

 division; 6, encysted form of single individuals; 7, conjugation of two individu- 

 als; 8, reproductive cyst; 9, cyst with peculiar contents whose further devel- 

 opment has not been followed (Brumpt). 



isms have not time to grow to the full size before dividing again. The result is 

 that many appear that are no more than 30 y. in length. In addition to multi- 

 plication by division, there is a sexual cycle of development with conjugation. 

 This was first pointed out by Gourvitsch,* studied by Lager and Duboscq,t and 

 further confirmed by Brumpt. | In the process of conjugation two individuals 

 come together, become attached lengthwise, and fuse into a single large organism 

 that forms a cyst several times as large as a balantidium, and with contents no 

 longer recognizable as such. The contents of this cyst eventually divide into a 

 number of spheres, but how these subsequently develop appears not to have been 

 determined. 



Habitat. — The balantidium is unknown except as a parasite of the colon. It is 

 very common in hogs and has been found in the orang-outang, in certain lower 

 monkeys (Macacus cynomolgus), and in man. 



* "Russ. Archiv. f. Path. klin. Med. u. Bact. St. Petersb.," 1896, quoted by 

 Braun. 



t "Archiv. de Zool. Exper.," 1904, 11, No. 4. 



I "Compt.-rendu de la Soc. de Biol.," July 10, 1909. 



