418 University of California P ublica tions in Zoology [Vol. 20 



7. A Giardia, resembling Giardia enterica, was recovered from 

 one of the rats in this series. As no cysts of this flagellate had been 

 detected in the feeding material, the infection in the stools used must 

 have been very light. 



8. The cysts of Councilmania lafleuri, Endolimax nana, lodamoeha 

 biitschlii, and Endamoeba dysenteriae recovered from this series of 

 rats were without any apparent racial or morphological change. 



9. The rats which became infected with C. lafleuri, Endolimax 

 nana, and lodamoeba biitschlii remained in apparent normal health. 



DISCUSSION AND CONCLUSIONS PBOM TABLE .5 



1. Twelve out of twenty-five, or 48 per cent of the rats fed a 

 mixed infection of E. coli and Councilmania lafleuri, became infected 

 with lx)th or one of these amoebae. 



2. Eighty per cent of the amoeba-free rats became infected while 

 only 27 per cent of the rats of unknown previous infection acquired 

 the amoebae. It is probable that the ones that became infected were 

 amoeba-free at the time of feeding. 



.3. The motile amoebae of C. lafleuri were easily distinguishable 

 by their hyaline pseudopodia while the motile amoebae of E. coli 

 showed the characteristic granular pseudopodia. The cysts of both 

 species were also mopphologically characteristic after being passed 

 through the rat, and presented no apparent structural change. 



DISCUSSION AND CONCLUSIONS FROM TABLE 6 



1. E. dyscntrriac, E. coli, and C. lafleuri, respectively, may be 

 transferred from rats experimentally infected with each of these 

 amoebae to uninfected rats. 



2. The cysts and motile forms of the amoebae maj' be recovered 

 without any apparent morphological change after transfer. 



3. None of the rats infected in this experiment suffered anj' 

 apparent pathogenic consequences during the time of the experiment. 

 This indicates that amoebae that have passed through a second series 

 of rats are no more virulent than those passed directly from man 

 to rats. 



