AMCEBA PROTEUS VS. ENDAMCEBA COLI 



ous bacteria to one made up of almost lOO per cent of 

 putrefactive bacteria by changing from a vegetarian diet 

 to a meat diet for a few days. The intestinal environment 

 may also be modified by the infection of the host with 

 other parasitic organisms, such as other species of 

 amoebae, intestinal flagellates, intestinal worms or vege- 

 table organisms such as yeast and Blastocystis hominis. 

 Drugs of various sorts and other agents may likewise 

 change the medium in which E. coli lives, for better or 

 for worse. How similar are the conditions that exist in 

 the free-living environment of A. profeus! The medium in 

 which it lives may be diluted by rain or concentrated by 

 drought. The nature and numbers of other organisms 

 with which it must share its habitat differ from time to 

 time; and pollution of the water may alter unfavorably 

 its surroundings, just as the administration of drugs may 

 modify the intestinal contents of man to the detriment of 

 E. coli. 



We know nothing about the behavior of E. coli within 

 its habitat, but it is safe to assume that this species 

 reacts to stimuli in its environment and that these reac- 

 tions are such as to insure its continued existence, other- 

 wise the race would cease to exist. These reactions are 

 no doubt different from those of A. proteiis, but they lead 

 to the same result. The conclusion is inevitable that in 

 morphology and in every process and activity that occurs 

 during their life-cycles, no essential differences are evi- 

 dent between the free-living Amwba proteus and the 

 parasitic Endamocba coli. 



A consideration of the geographical distribution and 

 methods of dissemination of the free-living and parasitic 



II 



