PLALE V: 
The figures, which represent various stages in the division of the 
pollen mother cells of Asclepias cornuti, were drawn with a mag- 
nification of 1750 diameters by means of a camera lucida, and re- 
duced to one-half of this magnification on the zinc plate. 
Fig. 1, Young pollen mother cell. 
Fig. 2, From mature pollen mother cell. 
Fig. 3, Prophase of nuclear division of pollen mother cell. 
Fig. 4, Early metaphase of nuclear division of pollen mother cell. 
Fig. 5, Anaphase of nuclear division of pollen mother cell. 
Cell plate in process of formation. 
Fig. 6, Advanced stage in formation of cell plate. 
Fig. 7, Completion of cell plate. Kinoplasm losing its thread- 
like structure. 
Fig. 8, Later stage in the disappearance of the kinoplasm. 
