l9L::iJ Kesscl: Experimental Infection of Rats and Mice 411 



The species of intestinal amoebae common to man, other than 

 E. dysenteriae, have never been experimentally established in rats 

 and mice. The present investigation also included an attempt to 

 infect these rodents with CottncHmania lafleuri Kofoid and Swezy 

 and to infect rats with E. coli (Losch), EndoUma-x nana (Wenyon 

 and O'Connor), and hjdamoeha biUschlii (Prowazek). 



It was apparent from the first that a detailed study of the amoebae 

 normal to the rat and mouse was essential before critical experimental 

 infections could be carried out satisfactorily. Accordingly, this work 

 was undertaken first, and to date three species of intestinal amoebae, 

 Councilmaniamuris (Grassi) Kessel, Councilmania decumani (Rudov- 

 sky) Kessel, and Endamoeha ratti sp. nov., have been found in rats 

 and mice and conclusions relating to their distinguishing character- 

 istics have been recorded in a separate paper (Kessel, 1923&). 



For assistance and guidance in the present work the writer is 

 glad to make acknowledgment to Professor C. A. Kofoid, under whose 

 supervision the investigation has been carried on, to Professor E. L. 

 Walker, who has been kind in giving counsel and advice, and to 

 Dr. Olive Swezy, whose suggestions have been of great value. Miss 

 Inez Smith, technician of the Division of Parasitology, California 

 State Board of Health, has generously cooperated in supplying 

 material from that laboratory for use in the feeding experiments. 



B. FEEDING EXPERIMENTS 

 I. Materials and Methods 



The rats used for the feeding experiments have been obtained 

 from the rat colony of the Department of Zoology, University of 

 California, and belong to the species Battus norvegicus (Erxleben). 

 For a history of the colony, see Kessel, 1923&. 



The rats chosen for experimental infection were young rats, about 

 two months of age. It was found during the experiment that male 

 rats are more suited to this type of work since it is easier to collect 

 faeces from them than from the females. 



Rats known to be free from amoebic infection of any type, and 

 other rats known to harbor an infection of Councilmania common 

 to the rat, were used. Amoeba-free rats were isolated by the epsom 

 salt method described by Kessel (lfl23f/.). These rats were kept 

 separate from those known to be infected with amoebae. 



