542 OX THE DIVISION OF NUCLEI Iff THE MYCETOZOA.. 



mounting3 show the nuclei in the stage described in my paper, 

 with no sign of karyokinetic change : in the other two mountings 

 every nucleus is dividing by karyokinesis, some are in the 

 spindle stage, in other parts of the preparation the nuclear plate 

 has divided and the daughter nuclei are in different degrees of 

 separation. 



This throws important light on the subject, and modifies the 

 conclusion expressed at the end of my paper. "Whether we can 

 accept this observation as explaining the entire process of nuclear 

 multiplication in the plasmodium, or whether, as seems probable, 

 there is also increase by direct division, is a point which requires 

 further investigation. 



EXPLANATION OF THE PLATES. 



Plate XXXV. 



Fig. 1. Resting nuclei from plasmodium (a) of Badhtomia utricularis, (b) of 



Trichia fragilis. 



Fig. 2. Nuclei apparently in process of direct division, from plasmodium of (a) 



Badhamia utricularis and (l) Trichia frag His. 



Figs. 3-8 represent successive stages of division of nuclei by karyokinesis in the 



young sporangium of Trichia f alia x m 



Fig. 3. Nuclei and " small nuclear bodies " an hour before nuclear division. 



Fig. 4. Nuclei in process of indirect division: a, "coil" stage; b, between 



the " coil" stage and the " nuclear spindle n ; d, e, " nuclear spindle," 

 the nuclear wall still persistent; c, probably the foreshortened aspect 

 of the spindle " d." (The chromatin elements in this fig. are repre- 

 sented as too globular and sharply defined.) 



Fig. 5. Division rather further advanced, the nuclear wall having disappeared : 



b, the spindle a seen from the pole. 



Fig. G. The " nuclear plate " is widely divided into two parts by the separation 



of the daughter segments. 



Fig. 7. The daughter nuclei have completely separated from one another, but 



are still disk-shaped. 



Fig. 8. A young spore containing a spherical nucleus and one small " nuclear 



body." 



XXXVI 



Fig. 9. Dividing nuclei, each contained in a mass of protoplasm of two spores' 



capacity, from the young sporangium of Comatricha Friesiana. 



Fig. 10. Swarm-cells of Beticularia Lycoperdon : a, active flagellate swarm- 

 cell ; b-g, successive stages in division of swarm-cell accompanied by 

 division of nucleus by karyokinesis. 



Note. — Figs. 1-9 are drawn from preparations killed with Flemuiing's fluid, 

 stained with picrocarmiue, and mounted in Canada balsam. Fig. 10 is drawn 

 from preparations killed and stained with acetic gentian-violet. All the figures 

 X 1000. 



