410 University of California Publications in Zoology [Vol. 20 



A. INTRODUCTORY AND HISTORICAL 



The present investigation was first attempted to determine whether 

 or not rats and mice could be experimentally infected with Enda- 

 moeba dysenteriae (Councilman and Lafleur). Most of the attempts 

 to infect rodents by feeding them with cysts of E. dysenteriae recorded 

 in literature prior to this time have been unsuccessful (see Kruse 

 and Pasquale, 1894; Werner, 1908; Dale and Dobell, 1917; Wenyon 

 and O'Connor, 1917; and Chatton, 1917, 1918). 



Lynch (1915), however, has recorded spontaneous and experimental 

 infection of rats in Charleston, South Carolina. He made his diag- 

 nosis of amoebae entirely from the motile forms and took no note 

 of the fact that there are intestinal amoebae normal to rats and mice, 

 the motile forms of which might easily be confused with E. dysen- 

 teriae, as both have hyaline pseudopodia. For an account of the 

 amoebae found in rats and mice see Grassi (1881), Wenyon (1907), 

 Brug (1919), Rudovsky (1921), and Kessel (1923&). See Wenyon 

 and O'Connor (1917) and Dobell (1919) for an account of the 

 pseudopodia of E. dysenterias. Lynch published no figures and 

 while the clinical symptoms he describes indicate the presence of 

 acute infections of E. dysenteriae, it seemed possible that his rats 

 might have died of some other infection common to rats, as implied 

 in the criticisms of Chatton (1917) and of Dobell (1919). 



In 1919, Brug reported what he thought was an infection of 

 E. dysenteriae in two wild rats in Java and further concluded that 

 he had been successful in establishing an experimental infection of 

 E. dysenteriae from man in a rat of the species Bins rattus. His work 

 seems to be conclusive, yet he entertains some doubt as to whether 

 the species he found in the rats and E. dysenteriae of man are 

 identical. 



Baetjer and Sellards (1914) reported successful inoculation of 

 guinea-pigs with E. dysenteriae, lesions of the bowel being found 

 at autopsy. Chatton (1918) concluded that guinea-pigs may be 

 infected with E. dysenteriae either by feeding cysts or by anal injec- 

 tions and that the infections, once established, are restricted to the 

 caecum. 



Huber (1909) succeeded in infecting rabbits by feeding them 

 cysts of E. dysenteriae and the examination of the rabbits at autopsy 

 showed a localization of amoebic ulcers in the caecum. 



