1916] Wilson: On flic Life-Hislorij of a Soil Amoeba 255 



peripheral chromatin came in (pi. 20, fig. 54). The case she mentions 

 in which the unequal nuclei are close together with pointed karyosomes 

 is analagous to the nuclei in plasmotomy (pi. 20, fig. 58). occurring 

 after multiple mito.sis, which are exactly comparable to some produced 

 in binary fission in which there may also be found the remains of the 

 plastin connection of the daughter nuclei (pi. 20, fig. 43). This .still 

 agrees with her material, for .she says that where there was much 

 amitotic division there were many multinucleated forms. Of course 

 it is possible that the laboratory conditions on agar plates were in some 

 instances pathological for the form she worked with, and so some of 

 the stages she figures are amitotic, but the evidence indicates that 

 amitosis does not occur. 



The comparison made above between the prophase stage and Miss 

 Hogue 's ' ' equal amitosis ' ' cannot hold if she has correctly interpreted 

 mitosis which she has characterized as promitotic. However her series 

 is incomplete, and there appear to be discrepancies in her interpreta- 

 tion of the stages she has figured (see her plate 16. figures 10-13), but 

 using her figures and changing the interpretation somewhat the analogy 

 drawn seems correct. 



4. ^Multiple Fission 



Jlultiple fi.ssion has not been observed in full, but there is evidence 

 that it occurs. The only cases of division observed in individuals in 

 which there had been multiple mitosis was plasmotomic. Multiple 

 mito.sis is very common in our multinucleate forms, which have been 

 found with two (pi. 19, figs. 22, 26), three (pi. 19, figs. IG, 20, 23), and 

 rarely four nuclei (pi. 19, fig. 18), but not more than three spindles 

 have been found. Wherry (1913), however, in the same species figures 

 individuals with two and four nuclei all in coincident mitosis, and 

 individuals with ten and more nuclei. Usually all nuclei are in the 

 same stage of divi.sion, but in a binucleate form one nucleus may divide 

 and the other not (pi. 19, fig. 16). Cytoplasmic division does not 

 follow, in .some cases at least, because in the resting condition indi- 

 viduals are often to be found with one large and two small nuclei. 



The spindles are ordinarily more or less parallel (pi. 19, figs. 20, 

 26), but they may be at right angles in the binucleate forms. In the 

 case of the parallel or nearly parallel spindles the division would 

 probably be plasmotomic (pi. 19, fig. 26), which has been found in the 

 case of forms with two .spindles. AVlien at right angles, the division 

 might be by coincident multiple fission, but this has not been observed. 



