STUDIES OF REPRODUCTIVE ELEMENTS: II. 331 



where spindle touches it. Acetic acid methyl-green preparation. 



Fig. 4. More advanced stage of division ; nucleus now duinbbell-sliiped 

 with archoplasms at its poles ; narrow line of protoplasm marking line of divi- 

 sion of animal seen in front of and behind central protoplasmic mass ; the latter 

 also constricted into two portions. Acetic acid methyl-green preparation. 



Figs. 5-9. Different stages of division, showing various pusitions of archo- 

 plasm in regard to those of nucleus. All acetic acid methyl-green preparations. 



Plate XII, 



(Figs. 10, 11, Si 12 represent fiàv'.y/oy; ; Figs. 13-19, .sporc-foriimtion.) 



Figs. 10 and 11. Further stages of division; tentacles already at stage 

 of fig. 11. Killed with Flemming's stronger fluid, and stained with Bohmer's 

 hematoxylin. 



Fig. 12. Portion of dividing individual with narrow protoplasmic connection 

 {p c) still visible ; tentacles grown much longer. Drawn from a living animal. 



Fig. 13. First stage of spore-formation ; archoplasm (a) as a granulated 

 mass lying close to nucleus {)i) ; dumbbell-shaped clear space within archoplasm, 

 which represents clear zone around a dividing centrosome. Drawn from living 

 animal. 



Fig. 14. Further stage of spore-formation about the same as that of fig. 4. 

 Acetic acid methyl-green preparation. 



Fig. 15. Still further stage of spore-formation ; division of nucleus now 

 nearly at an end, parts still connected by narrow bridge. Acetic acid methyl-green 

 preparation. 



Fig. 16. Central plasm and dividing nucleus at stage similar to that of last 

 figure ; drawn from living animal. 



Fig. 17. Four-nucleated stage of spore-formation ; archoplasms belonging to 

 nuclei in state of division, each forming large spindle. Drawn from acetic acid 

 methyl-green preparation . 



Fig. 18. Side view of stage slightly later than that of tig. 17. One of the 

 four nuclei, on right-hand of figure already divided into two daughter nuclei. (The 

 two dumbbell-shaped miclei, not represented in the figure, are also in a similar 



