AMCEBINA 



19 



using a warm table. E. coli is distinguished from E. buccalis and the 

 dysentery Amoebae by its lower refractive index, and especially by the 

 fact that, when motionless, there is no definite separation of the ecto- 

 from the endoplasm. This differentiation is observed during move- 



FIG. 2. Diagram of developmental cycle of E. coli (Losch), Schaud. (after Hart- 

 mann, slightly modified). 1, Young Amoeba. #, Adult Amoeba. 2a, .Reproduction by 

 fission. 3, Multiple nuclear division ; the chromatin has become aggregated into eight 

 groups at the surface of the nuclear membrane. 4, Completed nuclear division. 5, The 

 Amoeba has split up into eight daughter-individuals. 6, Commencement of cyst-formation, 

 7, First division of nucleus. 8, Consequent incomplete cell-division and formation of 

 chromides. 9, Formation by the chromides of two pairing nuclei. 10, Formation of two 

 reduced nuclei by each pairing nucleus. 11, Division of each of the reduced nuclei into 

 a free (male) nucleus and a stationary (female) nucleus. 12, By the merging of one free 

 and one stationary nucleus, two new nuclei are formed. 13, Adult cyst, containing eight 

 daughter-nuclei, the result of repeated division of the new nucleus. 14, Adult cyst, after 

 entrance into the intestine of a fresh host, discharging the eight sporogenously produced 

 Amoebae. 



ment, however, the pseudopodia proceeding entirely from the hyaline 

 ectoplasm. This phenomenon is of use in distinguishing between 

 E. coli and the leucocytes, the latter being devoid of ectoplasm. 

 The nucleus can generally be seen in the living organism. It is round 

 in shape, contains much chromatin, and is furnished with a thick 



