II. 



GENERAL MORPHOLOGY AND BIOLOGY OF AMCEB.E. 



BEFORE considering in detail the morphology and 

 life history of the parasitic amoebae of man it is 

 necessary to review briefly the general morphology 

 and biology of amoebae, as ignorance of the structure 

 and life history of saprophytic organisms belonging 

 to this sub-class of the Rhizopoda has resulted in 

 great confusion in the classification of the amoebae 

 of man. It should be constantly borne in mind that 

 the species occurring in man comprise but a minute 

 number when compared with the multitude of species 

 which are free-living and which are harmless and 

 incapable of a parasitic existence. 



The amoebae belong to the Protozoa, subphylum 

 Sarcodina, class Rhizopoda, sub-class Amoebina, and 

 order Gymnamoebida. These organisms are unicellu- 

 lar in type, all of their functions being performed 

 by the single cell. They occupy the lowest position 

 in the animal kingdom, but in one genus, Paramoeba, 

 a gradation may be traced to the next higher sub- 

 phylum, the Mastigophora. They are found very 

 widely distributed as free-living forms and as para- 

 sites within man and many of the lower animals. 



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