432 University of California Publications in Zoology [Vol. 20 



not been found below amphibians in the vertebrate scale, and 

 PentatricJwmonas, the most complex of the trichomonads proper of 

 mammals, has thus far been found only in man. 



The discovery by Kofoid and Swezy (1921«, &) of a type of 

 amoeba in man generically distinct from those previously described 

 from the vertebrates, naturally raises the question as to whether or 

 not species of this genus occur in other mammals. 



As a result of the investigations ofKessel (1923f/, b, c) as Univer- 

 sity Fellow, 1922-1923, in our laboratory, two additional species of 

 Councilmania have been distinguished in culture mice and rats of 

 our laboratory coIon_y. Experimental rearing of these species by 

 transfers to amoeba-free hosts and the like transfer and successful 

 culture of the human parasitic Protozoa, including Endamoeba coli 

 and Councilmania lafleuri (see Kessel, 1923&), have enabled us to 

 verify, supplement, and extend our observations on this genus. It 

 is the purpose of this paper to present a brief summary of these 

 results and relate them to the findings of Kofoid and Swezy (1921a, b) 

 and' to their subsequent work on Councilmania shortly to be pub- 

 lished in fuller detail. 



Acknowledgments are made to the Research Board of the Univer- 

 sity of California, to the Carnegie Institution, and to friends of the 

 University contributing to the support of this work, for funds which 

 have made the investigation possible. Much of our material has been 

 obtained in routine examinations made in the Division of Parasitology 

 of the California State Board of Health, in part by Miss Inez Smith. 



Councilmania Kofoid and Swezy 1921 



This genus is distinguished by a group of characteristics which 

 no other parasitic amoeba, or group of parasitic amoebae presents. 

 These are: (1) the karyosome is centrally located (in the resting 

 phase of the nucleus in the cyst), dispersed in numerous subequal, 

 discrete granules; (2) the nuclear membrane in cysts is generally 

 faint, and not often heavily or continuously encrusted with peri- 

 pheral chromatin; (3) the cysts bud in the caecum or colon of the 

 host by the escape of uninucleate amoebulae from a definite pore; 

 and (4) the pseudopodia are ectoplasmic, broad, rounded, very 

 hyaline, are formed very suddenly, and may persist as clear lobes 

 for extended periods of time. The three known species are all para- 

 sitic. The active stages are found in the caecum and colon and the 

 cysts also occur (in the rodent hosts) in the caecum. The cysts. 



