Organs and Fertilization in Picea excelsa. 367 
11. In the division of the central cell the spindle-fibres first 
arise from a clear court along the lower side of the nucleus 
and grow into the nuclear cavity where they are joined by 
the fibres from the small upper pole, which also originates 
outside of the nucleus but without any special court. The 
spindle, when fully formed, is more or less pointed at the 
lower end and somewhat blunt on the upper side. 
12. The nucleus of the ventral canal-cell when it is formed 
is much smaller than that of the egg, and very soon shows 
signs of disintegration. The ventral canal-cell rarely presents 
the appearance of a normal cell ; at the time of fertilization it 
may usually be seen as a small somewhat lenticular or cres- 
cent-shaped, deeply staining body, just beneath the neck-cells. 
13. The egg-nucleus, soon after it is formed, begins to 
increase in size, and moves down towards the centre of the 
egg. The mature egg-nucleus is more or less oval or ellip- 
tical in shape, and presents a deeply staining somewhat 
interrupted reticulum ; its average size is about 100 [xx 120 \x. 
When the ventral canal-cell is cut off, the vacuoles have 
nearly disappeared from the cytoplasm of the egg, and the 
proteid-vacuoles become numerous and prominent. About 
the time of fertilization the egg-cytoplasm presents a more 
coarsely granular structure. 
14. At the time of fertilization, the greater part of the 
contents of the pollen-tube including the two sperm-nuclei 
are discharged into the egg. The larger sperm-nucleus soon 
moves down and conjugates with the egg-nucleus. The 
sperm-nucleus first imbeds itself in the side of the egg-nucleus, 
and both nuclei retain their membranes intact for some time. 
The further changes in the conjugating nuclei have not been 
followed. The second sperm-nucleus remains unchanged in 
the upper part of the egg for some time, and probably dis- 
integrates there finally. The fate of the stalk-cell and the 
tube-nucleus has not been followed. 
15. The fertilized nucleus soon divides into two smaller 
nuclei. These two nuclei then divide simultaneously, and the 
four resulting free nuclei soon attain full size and move down 
