REPRODUCTION 33 



followed by autogamy, one zygote leaving the cyst 

 e.g. A. albida. This, according to Nagler, is 

 characteristic of the limax type, (b) Encystment 

 with internal changes resulting in the liberation of 

 amcebulae as described by Popoff. (c) Encystment 

 of multinucleate forms, and the production of 

 secondary nuclei, which eventually develop into 

 amoebulae after passing through an intermediate 

 flagellate stage. Possibly A. proteus multiplies in 

 this way. (d) Flagellate stages have been de- 

 scribed in Paramceba eilhardi, and by Metcalf 

 in small amoebae of the proteus type, (e) In 

 A. diploidea and A. binucleata, reproduction of a 

 complicated character has been described. 



In the species under consideration, however, we 

 have so far observed only binary fission, multiple 

 fission, budding, and conjugation. No flagellate 

 stage has been observed during four months' work 

 with cultures with sterile precautions, although, 

 previously to this, various flagellates and masti- 

 gamceb&e had appeared frequently. While ex- 

 cy station has been watched some hundreds of 

 times, only one amreba has been seen to escape 

 from a single cyst on each occasion. 



Binary Fission (PI. VIII.). The complete cycle 

 has been watched on many occasions and is by far 

 the commonest mode of reproduction. The division 

 is not always into two individuals of equal size, 

 there being every gradation between this and the 

 process of budding. By the jelly method the 

 nucleus is always in view and can be seen to 

 become first ovoid and then elongated, the centre 

 snapping either before or as the body of the amoeba 

 separates. Preparations containing dividing forms 

 iv 3 



