414 



TJniversity of California Puhlications in Zoology [^^ol. 20 



was a severe lung' infection which was the apparent cause of the 

 death of the rats. Smears and sections made from the infected parts 

 of the lungs revealed no amoebae. 



6. The type of lung infection found in these rats is the most 

 common cause of death among rats in the rat colony in the Depart- 

 ment of Zoology. During the period in which the four of the eleven 

 rats infected with E. dysenteriae died, one rat infected with E. coli 

 and three from the colony of one hundred and fifty uninfected rats 

 died of the same lung disease. Thus the mortality among the eleven 

 rats infected with E. dysenteriae was four and the mortality among 

 all the other experimental and uninfected rats of the rat colony, or 

 a total of two hundred and twenty-five rats, was also four. It seems 

 probable that the resistance of the rats infected with E. dysenteriae 

 was so lowered that they were more susceptible to the lung infection. 

 It is significant in this connection to note that a rabbit fed cysts of 

 E. dysenteriae by Chatton (1918) died of a lung infection. 



7. The course of the infection of E. dysenteriae among the rats 

 in this experiment was the chronic rather than the acute type which 

 seems to be the common type of amoebic infection found in kittens. 

 Seven of the rats infected with E. dysenteri-ae were in apparent health 

 at the time the last examination was made, though they all showed 

 the presence of cysts. 



8. Motile amoebae, mononucleate cysts, binucleate cysts, and four- 

 nucleate cysts of E. dysenteriae were recovered from the rats, and 

 these were without any apparent morphological or racial change from 

 their previous status in man (pi. 38, figs. 7-12). 



Results Obtained rEOM Feeding White Mice with Cysts or E. dtsenteeiae 



AND OF COUNCILMANIA LAELEDKI 



