MORPHOLOGY AND BIOLOGY. 23 



The exact mechanism of the origin of the pseudo- 

 podia has been studied by many observers, and 

 numerous theories have been brought forward to ex- 

 plain this interesting phenomenon. However, it may 

 be stated that we are yet ignorant of the real 

 mechanism of pseudopodia formation. 



In one genus of amoebae, i.e., Paramceba, delicate 

 ftagella have been observed during certain stages of 

 development. Organisms belonging to this genus 

 possess both an amoeboid and flagellate cycle of de- 

 velopment. During the amoeboid cycle they move 

 about by means of pseudopodia, while during the 

 flagellate cycle locomotion is accomplished by means 

 of a flagellum w r hich apparently takes its origin from 

 some portion of the periphery of the organism. 



METHODS OF REPRODUCTION. Although these 

 organisms, from a morphological standpoint, illus- 

 trate the most simple form of animal life, they possess 

 several methods of reproduction, some of them of 

 great complexity. These methods are: simple 

 division, schizogony, gemmation, and reproduction 

 within a cyst. The first three methods occur during 

 the vegetative stage of existence, the latter, only when 

 conditions arise which are unfavorable to such ex- 

 istence. Schizogony and reproduction within a cyst 

 are confined to certain species, and gemmation ap- 

 pears to be peculiar to Entamceba Mstolytica, but 

 simple division occurs in all species. 



