706 



Balantidium Coli 



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 satisfac- 

 torily studied while alive. To stain it a drop of the fluid 

 containing the balantidia is spread upon a slide and per- 

 mitted 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-hematoxylon. 

 The cilia usually do not show. 



Fig. 234. Reproduction of Balantidium coli: 1-5, Asexual reproduc- 

 tion by division; 6, encysted form of single individuals; 7, conjugation 

 of two individuals; 8, reproductive cyst; 9, cyst with peculiar contents 

 whose further development, has not been followed (Brumpt). 



Reproduction. This commonly takes place by karyoki- 

 nesis, followed by transverse division, and in cases of ex- 

 perimental infection so rapidly that the organisms have not 

 time to grow to the full size before dividing again. The result 

 is that many appear that are no more than 30 (* in length. 

 In addition to multiplication by division, there is a sexual 

 cycle of development with conjugation. This was first pointed 



