The Early Stages of Spindle-Formation in 
the Pollen-Mother-Cells of Larix. 
BY 
CHARLES E. ALLEN, 
Instructor in Botany in the University of Wisconsin. 
With Plates XIV and XV. 
Introduction. 
N UCLEAR division in the pollen-mother-cell of Larix 
davurica , Trautv., was described and figured by Belajefif 
(’94). He finds, in the early prophases of the first mitosis, 
a system of radial fibres extending from the nuclear membrane 
to the cell periphery. Later, a close felt-like layer of fibres, 
or meshes, appears just without the nucleus ; some fibres are 
still left in the peripheral cytoplasm. This arrangement, he 
suggests, may have resulted from a drawing together of the 
radial fibres about the nucleus ; but he finds none of the 
intervening stages. The fibrous material already present 
within the nucleus increases in amount, forming a dense net- 
work ; the nuclear membrane disappears, and with it the 
distinction between intra- and extra-nuclear fibres. The 
peripheral fibres group themselves so as to converge toward 
points (one to four in a section) near the cell-wall, and the 
fibres of the central mass become so arranged with reference 
to these points as to form a multipolar spindle. Bundles of 
fibres connect the chromosomes, lying in the central region of 
[Annals of Botany, Vol. XVII. No. LXVI. March, 1903.] 
U 
