1. In both species of pines studied, the interval between pollination and fertilization is almost exactly one year. 2. The resting nucleus of the central cell contains several nucleoli and an apparently homogeneous, coarsely granular, metaplasmic substance forming an interrupted reticulum. 3. During mitosis the chromatin arises from a portion of this substance, appearing as irregular clumps that soon give rise to deeply staining, convoluted threads with a moniliform structure. These form the chromosomes, which gradually shorten and thicken. An intranuclear, multipolar, diarch spindle arises, surrounded by metaplasm not previously involved in the formation of chromosomes or the spindle itself. 4. At the equatorial-plate stage the chromosomes, 12 in number, are split longitudinally and show conspicuous median fiber-attachment points. The daughter chromosomes twist about each other, particularly when they begin to separate. They are V-shaped or narrowly U-shaped as they move toward the poles. 5. The ventral canal nucleus may or may not disorganize before reaching the resting condition. As the egg nucleus enlarges, the metaplasm reappears, soon completely obscuring the chromatin. It then exhibits nearly the same structure as the resting nucleus of the central cell. A variable number of nucleoli are present. 6. The male nucleus consists of the same kind of metaplasmic substance as the egg nucleus, but contains no nucleoli. It sinks into the egg nucleus, the chromatin differentiating in each of the conjugating nuclei after the common membrane separating them breaks down. 7. The male and female chromatin, each surrounded by its own group of spindle fibers, consists of attenuated, very slender, convoluted strands. A common multipolar, polyarch spindle is formed; this becomes diarch as the chromosomes, arising in two groups, come together. 8. The paternal and maternal chromosomes cannot be distinguished from each other when the equatorial-plate stage has been reached. As they shorten and thicken, they display prominent median fiber-attachment points and conspicuous longitudinal splitting. 9. During the metaphase of the first embryonal mitosis, 24 chromosomes are present, half derived from the male nucleus and half from the female. The longitudinal segments of each split chromosome tend to twist about each other. 10. During the anaphase, 24 V-shaped or narrowly U-shaped daughter chromosomes pass to each pole, as in any other somatic mitosis.