No. 460.] STUDIES ON PLANT CELL.— V. 231 
The fibrille organize a multipolar spindle which is very vari- 
able in form, sometimes with broad poles of a multipolar diarch 
(Fig. 17, d) and at other times almost as pointed as in a typical 
bipolar spindle (Fig. 17, e). There are, of course, no centro- 
somes and the entire spindle in essentially of intranuclear origin. 
The history of its development recalls Miss Williams’ account 
of the spindle in the pollen mother-cell of Passiflora (Sec. III, 
Amer. Nat., vol. 38, p. 738, 1904). During spindle formation 
the spirems of the sperm and egg nuclei can be readily distin- 
guished as was described by Blackman (98) and Chamberlain 

Fic. 17. — Fertilization in Pinus strobus. a, conjugating gamete nuclei; 4, > gamete nuclei 
still rear with nuclear palate dis tinct, the maternal and paternal chroma atin in 
two spire , the nuclear membranes have 
together aa by the fibrilla which will organize the first segmentation spindle; d, 
prophase of the first segmen ntation spindle, of the multipolar diarch type, paternal and 
men spireins still distin; " — of fret ay entation mitosis, maternal a: 
nd 
split in the middle region (after 

Prison, : 104). 
('99), but after the two sets of chromosomes are formed (twelve 
of each) the latter are brought so closely together at metaphase 
of mitosis that the paternal and maternal cannot be separated. 
All of the chromosomes are exactly alike and there is nothing in 
the form or size to distinguish one from another as certain 
