BALANTIDIUM COLI 123 



Solowjew, however, the parasites penetrate the intestinal wall, and 

 give rise to ulcerations which may extend deeply into the subserosa ; 

 this author states that he has also seen them in the blood and 

 lymphatic vessels of the intestinal wall. Strong and Musgrave (Bull. 

 Johns Hpk. Hosp., 1901, xii.) have made similar observations, as 

 also has M. Askanazy (Vortrag. i. d. biol. Sect. d. Phys. Ges. 

 Konigsberg, Pr., 1902). According to Stokvis, Balantidium coli 

 occurs also in the lung ; at all events this author states that he 

 found one living and several dead paramaecia (?) in the sputum 

 of a soldier returned from the Sunda Islands, and who was 

 suffering from a pulmonary abscess. 



Since Leuckart confirmed the frequent presence of Balantidium 

 coli in the rectum of pigs, and corresponding observations were 

 made in other countries, the pig is universally considered to be the 

 means of the transmission of balantidium to man. The encysted 

 stages alone can subserve transmission, because, according to 

 all observations, the free parasites have a Very small power of 

 resistance ; they even perish when the faeces have become cool, 

 they cannot live in ordinary, or slimy, or salt water ; and as they 

 are killed by acids even when much diluted, it follows that they 

 could not pass through the normal stomach alive except under 

 the most exceptional circumstances. The pigs, in whose intes- 

 tines the balantidium appears to cause no disturbances, evacuate 

 numerous encysted balaritidia with the faeces, and their occasional 

 transference to man brings about their colonisation there, but 

 apparently only when a disease of the colon already exists. No 

 colonisation takes place in healthy persons, as has been demon- 

 strated by Grassi and Calandruccio from experiments made on 

 their own persons. 



Experimental transmission of the free parasites to animals (per 

 os or per anum) yielded negative results, even in the case of pigs ; 

 only Casagrandi and Barbagallo had positive (as well as negative) 

 results ; they employed healthy young cats, or cats in which 

 catarrhal entero-colitis had been artificially induced (and which in 

 other experiments is apt to cause the death of the animals experi- 

 mented upon in about six or seven days), or finally cats that had 

 dilatation of the rectum with alkaline reaction of the faeces. The 

 experiment to infect three healthy cats by injecting human fieces 

 containing balantidium in the rectum proved negative, in so far 

 as the faeces of the experimental animals had an acid reaction and 

 contained no balantidia, but at the autopsy performed after eight 

 days a few ENCYSTED parasites were found in the mucus of the 



