BALANTIDIUM COLI 



551 



nucleus is small, round, and vesicular. The size of Balantidium coli 

 varies between 60 to 100 micra, its width between 50 to 70 micra. 

 Reproduction occurs by division, budding, and conjugation. In 

 division the macronucleus divides amitotically, the micronucleus 

 mitotically. Leuckard has described encystation of the parasite. 

 If this is to occur the cilia are gradually lost, except a few near the 

 mouth, and the body finally becomes perfectly round and surrounds 

 itself with a heavy capsule. Encystation has also been noticed after 

 conjugation. Very probably the infection is transmitted from one 

 host to another in the encysted stage of the parasite. The organism, 

 according to a monograph of Strong, has been found in about 150 

 cases in man, generally in cases of obstinate diarrhea. In some of 



FIG. 187 



Balantidium coli: 1, 2, stages of division; 3, conjugation. (After Leuckart.) 



the observed cases death followed. Most authors look upon balan- 

 tidium as a harmless commensale of the hog and occasionally man, 

 but some, like Strong, believe that it may be the cause of diarrhea! 

 intestinal disturbance and the ulcerations accompanying it. Strong 

 and others have found the balantidium in the intestinal tissues, and 

 there is no doubt that the organism engulfs and digests the blood 

 corpuscles of its host. The author has seen a case of intense balan- 

 tidium infection in a Filippino, but since the infusorium was associated 

 with an uncinaria infection, it was impossible to decide to which 

 of the two the pathologic disturbance was mostly due. Brooks has 

 described an epidemic among the orang-utangs of the New York 

 Zoological Garden, in which balantidium was found in large numbers 

 in the stools. Several of the animals died and the postmortem 

 examinations showed ulcerations in the intestines and balantidium 

 in the tissues. 



