112 BACTERIOLOGY. 



lytica, a protozoan parasite, larger than any of the bac- 

 teria that have been studied. It is composed of an 

 outer clear zone, a granular inner zone which contains 

 the nucleus, and a cavity called a vacuole. It moves 

 by extending a portion of the outer clear zone, called 

 a pseudopod, into which the rest of the cell body flows. 

 The pseudopods may also embrace small particles of 

 food and make them part of their bodies. The amebse 

 are very sensitive to changes in temperature, and 

 motility can be seen only at body temperature. Repro- 

 duction takes place either by simple division or by the 

 formation of smaller cells called daughter-cells, which 

 are set free and develop into parasites. 



The infection with amebse comes from drinking 

 infected water and possibly from eating uncooked 

 vegetables that have been washed in infected water. 

 After being ingested the amebee lodge in the intestine 

 and cause inflammatory changes that lead to ulcera- 

 tion. It is not uncommon for the amebse to be carried 

 from the intestine to the liver, where they may cause 

 abscesses. The stools contain the amebee and, to pre- 

 vent the disease from spreading, the stools must be dis- 

 infected with 5 per cent, solution of carbolic acid. In 

 countries where the disease prevails, all water used for 

 drinking purposes should be boiled, and no uncooked 

 vegetables eaten unless washed in boiled water. 



The diagnosis of amebic dysentery is made by 

 finding the amebae in the stools. This can be done by 

 examining under the microscope the mucus or pus in 

 the stool or that obtained by passing a rectal tube high 



