NUCLEI IN THE MTCETOZOA. 530 





whether the spores would have retained their vitality for so Ion 

 a period. That they had done so was soon proved. On Dee. 3 

 I shook some of the spores into a watch-glass, giving one drop of 

 methylated spirit to expel the air from among them, and adding 

 about 10 minims of filtered rain-water; in a few hours the 

 swarm-cells were hatched in great numbers ; on the following day 

 a large proportion of the spores were empty, perhaps nine-tenths 

 of their number, and the water was milky with the multitude of 

 swarm-cells in active motion. A drop of this water was placed ^/^ 

 on a glass slide and dilute acetic gentian-violet was added ; the 

 swarm-cells were instantly killed, retaining their natural form 

 with the flagellum extended ; in these the nuclei were faintly 

 stained, but here and there a few cells could be noticed with 

 the flagellum withdrawn and in process of dividing ; some 

 were of globular form, others had become oblong, and others 

 again were constricted or were about to separate. In all these 

 stages the nuclei were deeply stained, so that they could at once 

 be distinguished anions the host of flagellated swarm-cells by 

 which they were surrounded, and each darkly-stained nucleus 

 was seen to be in one or another state of karyokinetic change. 



In some of the spherical ceils the nuclear plate had formed, 

 and was seen, in profile, to consist of about six segments 

 (PI. XXXVI. fiir. 10); in others division of the plate had 

 taken place and the nuclear halves had just separated (fig. 10, c); 

 in favourable instances the spindle-fibres could be detected con- 

 verging to the poles of the spindle. In the oblong forms the 

 two nuclear halves had retreated to the distance of about four 

 times their diameter, and where the stain was of the right intensity 

 the spindle-fibres could be distinctly seen connecting the daughter 

 nuclei (fig. 10, d). Where separation of the cells had nearly 

 occurred the still deeply-stained daughter nuclei had a discoid 

 or crescentic outline, and took an excentric position in the 

 daughter cells at the most distant point of divergence from one 



another (fig. 10, g). 



After the swarm-cells have completely divided, the nuclei soon 

 lose the property of retaining the deep stain ; it is only while 

 the cells remain attached to each other, though ever so slightly, 

 that their nuclei are conspicuously darker than those of the neigh- 

 bouring cells. 



On the third day after wetting the spores, the swarm-cells were 

 in vast abundance in the watch-glass, and mostly smaller in size 



