322 UR. T. GOODEY ON 



bacteria, and ia those fonns exhibiting the slug-like appearance 

 the posterior end is frequently covered by an adherent mass of 

 bacteria (fig. 49). 



The nucleus consists of a large karyosome, which is separated 

 from the nuclear membrane by a clear zone and an outer ring of 

 faintly staining granules. The latter may apparently occur as 

 very small discrete particles, as in fig. 49, or as a single ring of 

 small blocks, as in fiuf. 50. I have not succeeded in making out 

 any connecting strands between the karyosome and the nuclear 

 membrane. It resembles the nuclei of Amwba glebce and Amcuba 

 laiiiellipodia in possessing the ring of faintly staining granules. 



(b) Reproduction. 



The animal ceases to wander about and comes to rest, at 

 the same time becoming spherical. I have not made out 

 pseudopodia in any of these globular dividing forms. The 

 earliest stage in the division of the nucleus which I have dis- 

 covered is shown in tig. 50, where the karyosome has broken 

 down into four principal masses. This fragmentation of the 

 karyosome is continued until the central part of the nucleus 

 originally occupied by the karyosome, or an area slightly larger 

 tha,n this, becomes filled with a mass which appears to be made 

 up of very faintly staining particles, amongst which are lodged 

 the rather more deeply staining gi'anules produced by the dis- 

 integration of the karyosome. I cannot say whethei- the ring of 

 faintly staining granules occurring in the " resting " nucleus 

 takes any part in the division or whether they disappear. 

 Dobell says that in Amoeba glebce they entirely disappear, and it 

 may be the same in my organism. The fine particles produced 

 by the fragmentation of the karyosome stain much less intensely 

 than the original karyosome. They gradually aggregate and 

 jjroduce somewhat larger gnxnules, which become connected vip 

 into a sort of chain formation, which lies in an irregular manner 

 among the mass of linin particles. The nuclear membrane does 

 not disappear, and does not seem to become any less distinct than 

 during the " resting" condition of the nucleus. 



The chain of chromatin granules or chromosomes, as they may 

 perhaps be called, approaches the equatorial I'egion of the nucleus, 

 where it ultimately becomes disposed in the form of a ring 

 (fig. 53). At this stage the first indications of a spindle make 

 their appearance, becoming elaborated out of the linin matrix in 

 which the ring of chromatin granules has been lying. The ends 

 of the spindle are at first broad and rather flattened, but later 

 on they become very sharply pointed. The plane in which the 

 long axis of the spindle lies is slightly oblique to the horizontal 

 plane of the nucleus. This is well seen in fig, 54, where the two 

 ends of the spin<lle extend beyond the limits of the nuclear 

 membrane which is represented in optical section, one end being- 

 over and the other under the nuclear membrane. 



