Fertilization in Finns Strobus. 471 
celled stage of the proembryo has been reached. These eight 
nuclei are surrounded by a deeply staining substance which' 
extends out from each nucleus in irregular strands. This 
substance finally comes to lie in the lines of the future 
cell-walls, and is evidently transformed into cell-wall. 
The number of chromosomes in the nucleus of the ventral 
canal-cell, in the nuclei of the sheath-cells, and in the egg- 
nucleus has been found to be 12, while the mitotic figure, in 
the first division following fertilization, shows 24 chromatic 
segments. 
It is interesting to note the many points of similarity between 
fertilization as it has been observed in Pm?is, and the processes 
known to take place during fertilization in some animals. (1) 
The egg in Pinus is very large and is abundantly supplied 
with nutritive spheres. (2) The sexual nuclei do not fuse, 
and no structure which could properly be called a segmenta- 
tion-nucleus is ever formed. (3) An achromatic nuclear recti- 
culum becomes very prominent in the sexual nuclei during the 
prophase of division. (4) The chromatin of the sexual nuclei 
forms two definite groups which remain distinct until meta- 
kinesis. (5) Two chromatic groups, representing respectively 
the paternal and the maternal chromatin, appear in the second 
division following fecundation ; and the indications are that 
they will again occur in the third division and perhaps are 
characteristic of all the divisions which take place within the 
oosphere. (6) The nuclei, which enter the egg from the 
pollen-tube but play no part in fertilization, show a tendency 
to divide mitotically. 
I am pleased to express my gratitude to Professor George F. 
Atkinson for his most helpful advice and encouragement, 
and his never-failing kindness, throughout the entire progress 
of these studies. 
