1903] STUDIES [IN SPINDLE FORMATION 99 
PLATE XV.— Fics. 12-17, Dtsporum Hoekorz. 
F1G. 12. Spore mother-cell showing transformation of cytoplasm into 
a weft of kinoplasmic fibrils not parallel tothe nuclear wall. 
Fic. 13. Later development of kinoplasmic zone; the weft not uniform 
but much more abundant on one side of nucleus. 
Fic. 14. Weft in the form of irregular sharp-pointed primary cones; 
their fibrils very much elongated and convergent. 
Fig. 15. Fibrils forming cones more independent of one another and more 
sharply defined. 
Fig. 16. Nuclear membrane gone; cones united at apices; fibrils joined 
with chromosomes; the latter taking position at the equator. 
Fig. 17. Mature bipolar spindle. 
PLATE XVI/,— Fics. 18-23. Hesperaloe Davyt 
Fig. 18. Pollen mother-cell, showing formation of kinoplasmic zone quite 
uniform in thickness. 
Fig. 19. Later irregular outward growth of kinoplasmic zone; the meshes 
composing it point in the direction of the outward projection or primary cone. 
Fic. 20. Nuclear wall breaking down; inward growth of fibrils from the 
base of the cones with which the chromosomes are now in contact. 
Fig, 21. Typical multipolar spindle after entire disappearance of nuclear 
membrane. 
Fig, 22. Cones collecting in two groups and uniting at their apices so 
as to indicate position of bipolar spindle. 
1G, 23. Mature bipolar spindle. 
PLATE XVII,—FiGs. 24-34. Hedera heltx 
Fic. 24. Young pollen mother-cell showing early stage in the formation 
of kinoplasmic weft. 
1G. 25. Later stage of kinoplasmic zone, indicating by one-sided growth 
the beginning of one of the primary cones. 
Fic, 26. Four more fully developed primary cones in the same plane; 
fibrils Composing them much more clearly defined and convergent. 
Fic. 27. Somewhat older stage with several cones in the same plane; 
fibrils very clearly defined and cones almost fully developed. 
Fic. 28. Nuclear wall gone; chromosomes in contact with spindle fibrils ; 
‘cones partially united in two groups indicating future position of bipolar 
spindle. 
FIG. 29. Mature bipolar spindle. As there is a large number of chro- 
mosomes, the spindle is very wide at the equator. 
Fig. 30. Chromosomes at the poles of spindle; nuclear wall not yet 
formed around daughter nuclei; many continuous fibrils between the daughter 
nuclei ; also a series of short radiating mantle fibrils, which extend out in all 
‘directions from the masses of chromatin. 
