FREE-LIVING AMCEB.E 149 



Of the two, E. histolytica has priority, and hence, 

 probably, will persist, though the stages described 

 by Viereck in 1907 as E. tetragena were undoubtedly 

 the clue to the remarkable series of forms that con- 

 stitute the life-cycle of the Entamceba. 



Dealing first with the Amoebae recorded from 

 water, moss, and similar vegetable material, there is 

 little to say, for they present the characters described 

 for amoebae generally. They possess remarkable 

 powers of resisting desiccation, and when the pond 

 or vegetation dries up, they encyst and remain thus 

 until the return of more favourable conditions. The 

 cyst at first possesses one large nucleus. This 

 divides into two, and the daughter nuclei repeat the 

 division until a number of nuclei are present. Cyto- 

 plasm collects round each of the nuclei, a cyst wall 

 may or may not enclose each, and a collection of 

 daughter amoebae is thus produced. Sometimes the 

 parent cyst wall crumbles down and the tiny 

 daughter forms are liberated. At other times, on 

 the return of moisture, the parent cyst wall breaks 

 down and the daughter cysts pass out from it. The 

 little amoebulce, if within daughter cysts, escape from 

 them in various ways, and can proceed at once to per- 

 form all the functions of their ancestors. Occasion- 

 ally large amoebae under adverse circumstances are 

 said to depend for protection on the hardening of 

 their outer layer. 



The Amoebae found in the bodies of animals are 

 very numerous and have been recorded from almost 

 all the larger groups of organisms. Those present in 

 man are of most interest. They are not restricted 



