VIII, B, 1 Walker: Balantidicidal Activity 3 



The conditions for testing the balantidicidal action of drugs 

 and chemicals in vitro are extremely favorable. Balantidium 

 coli, under favorable conditions, remains alive and active in 

 the faeces for several days. Moreover, -we have, in the active 

 locomotion and the persistent activity of the oral cilia during 

 life, and in the disintegration of the protozoon at death, the 

 most delicate and at the same time the most striking indicators 

 of injury to, and death of, the parasite. The active movements 

 of Balantidium coli usually persist up to, and the movement 

 of the oral cilia even after, the beginning of disintegration of 

 the protozoon. Death of the parasite is usually accompanied 

 or closely followed by disintegration. This disintegration takes 

 place by the extrusion of the protoplasm through the oral, and 

 sometimes also the anal, orifice of the protozoon. The process 

 of protoplasmic extrusion is closely correlated with the balan- 

 tidicidal activity of the substance employed. In slightly toxic 

 solutions the balantidia exhibit only the protrusion of small 

 buds of protoplasm, the organism still maintaining its active 

 movements. In more toxic solutions the extrusion of the pro- 

 toplasm becomes progressively greater until the protozoon col- 

 lapses. And in eminently toxic solutions this disintegration 

 becomes explosive in character, the ectosarc being ruptured 

 and the whole contents liberated at once. An exception to this 

 disintegration of balantidium occurs in the presence of certain 

 chemicals, such as the salts of mercury, which act as a fixative. 

 In this case the protozoon is killed and fixed with cilia extended. 



There exist records of a few balantidicidal tests performed 

 in vitro, but these tests have been limited to acids, alkalies, 

 alcohol, and a few common salts, and definite quantitative 

 determinations of the balantidicidal limits of dilution of the 

 substances have not been made. Thus Glaessner (1908) made 

 the following crude tests of the action of a few chemicals on 

 Balantidium coli: 



Experiment. Result after 6 hours. 



1. Ten grams of fseces were added to 40 cubic Balantidia mostly dead, 



centimeters of water at 40° C. a few were living. 



2. Ten grams of faeces were added to 40 cubic Some of the balantidia 



centimeters of 0.6 per cent NaCl. dead. 



3. Ten grams of faeces were added to 40 cubic Balantidia dead. 



centimeters of 1 per cent alcohol. 



4. Ten grams of faeces were added to 40 cubic Balantidia dead. 



centimeters of 5 per cent alcohol. 



5. Ten grams of faeces were added to 40 cubic Balantidia dead. 



centimeters of 0.3 per cent NaCl. 



