CANNIBALISM IN AMOEBA 675 



difference was observed between the sizes of the nuclei and the 

 endosomes of amoebae and spheres of the same size ; but, of 

 course, the bigger spheres showed bigger nuclei than the 

 smaller ones, A comparison of these measurements of the 

 nuclei of the spheres with those of the nuclei of the amoebae 

 was very striking : 



Diameter of the amoeba 60-130 /x Diameter of sphere . 20-26 /x 



Diameter of imcleus of Diameter of nucleus of 



amoeba . . . 7-9 /Lt sphere .... 6-8 fx 



Diameter of endosome of Diameter of endosome of 



amoeba . . . 4-7 lu. sx^here .... 4-5 ft 



The correspondence was very remarkable, especially when it 

 was noted that the sphere scarcely differed in any respect, except 

 in shape, from the amoeba and was almost indistinguishable 

 from the rounded-off forms of the latter. 



While it was inside the vacuole, the sphere was never seen 

 to move in any way by its own efforts. It was not ciliated nor 

 flagellated, nor did it put out pseudopodia, but maintained, in 

 most cases, a perfectly even spherical contour, although a few 

 cases were seen in which its outline was oval or even irregular 

 (PL 29, figs. 8 and 10). The spheres were sometimes rolled 

 over and over in the vacuoles by the streaming movements 

 of the protoplasm, in which case the whole vacuole probably 

 rolled about as a whole. But, in one instance, when the 

 streams of protoplasm were very active along the sides of the 

 vacuole, the enclosed sphere was seen to rotate in the opposite 

 direction. 



The spheres could be squeezed out of the amoebae by gentle 

 pressure on the cover-glass, and then lay quite motionless and 

 spherical in the water near by. Tw^o such squeezed out on 

 July 21, 1920, at 2.30 p.m., remained quite unchanged until 

 11 a.m. on the following day. It was also noticed then that 

 numbers of such free, motionless spherical bodies, resembling 

 rounded-off amoebae, could be found in the cultures. Doflein 

 (9) states that, in old cultures of Amoeba vespertilio 

 which had become foul and acid in reaction, the amoebae tended 

 to round off and to die. Two questions therefore arose : 



