VIII, B, 5 Walke)-: Experimental Balantidiasis 337 



and 1 of the pigs, and the stools of the pig contained blood and 

 balantidia filled with red blood corpuscles. At the necropsy 

 performed on the parasitized monkey, balantidia were found 

 in the large intestine from the csecum to the anus, but there were 

 no lesions. In the necropsy of the infected pig the author 

 states that lesions were present in the large intestine which 

 were identical with those described by Strong, Askanazy, and 

 others in human cases. No histological examinations appear 

 to have been made in any of Brumpt's experimental infections 

 to determine the etiologic relation of the balantidia to the lesions. 



On the other hand Ekecrantz (1869), Wising (1871, 1885), 

 Rapchevski (1880), Lavrovskaya (1890), Afanasyeff (1891), 

 Casagrandi and Barbagallo (1896), Chigayeff (1898), Valayeff 

 (1898), Zhegaloff (1899), Chichulin (1900), Strong (1904), and 

 Bowman (1911) have failed in their attempts to infect animals 

 (cats, rabbits, dogs, pigs, monkeys) with Balantidium coli. 

 Casagrandi and Barbagallo state, as a conclusion from numerous 

 experiments, that the parasites could sometimes live in the in- 

 testine of cats if a catarrhal condition was first produced, but 

 that they were incapable of producing independent disease in 

 the intestine. Bowman injected fresh faeces from a case of 

 severe infection in man many times into the rectum of monkeys 

 suspended by the lower extremities in order that none of the 

 infective material could be evacuated. He performed a colotomy 

 on another monkey and injected 20 cubic centimeters of a balan- 

 tidial stool on two occasions into the colon. And, finally, tissue 

 from an ulcer containing balantidia was inserted beneath the 

 mucosa of the colon of a monkey and sutured in place. In every 

 case the Results were negative; the parasites were never found 

 in the faeces of the experimental animals. 



The following infection experiments on monkeys were under- 

 taken to discover the reason for the discrepancy in the results 

 of Brumpt and of other authors in their attempts to infect 

 animals with Balantidium coli, to determine the identity or non- 

 identity of Balantidium coli sids ^ with Balantidium. coli hominis, 

 and to obtain further information on certain obscure points in 

 the etiology, pathology, and endemiology of balantidiasis of man. 



The monkeys used in these experiments were healthy indi- 

 viduals of the common species found on the Island of Luzon, name 

 undetermined. Some of them had been in captivity for some 



' Suis or hominis is attached to the specific name throughout this paper 

 for convenience in distinguishing the pig and the human strains and not 

 for the purpose of indicating taxonomic varieties of Balantidium coli. 



