35 2 Miyake, — On the Development of the Sexual 
gonium, and affirmed Hofmeister’s observation regarding the 
presence of a closed pit at the apex of the tube. Three years 
later Strasburger (72) made a further contribution to the 
embryology of Picea by describing the process of embryo- 
formation in Picea excelsa. 
In 1878 Strasburger observed two ‘ primordial cells’ in the 
pollen-tube of Picea excelsa , and mentioned that these cells 
dissolve one after another before fertilization takes place ; 
later, the sperm-nucleus, which, he thought, was formed from 
the contents of the tube, appears in the upper part of the egg 
and finally fuses with the egg-nucleus. In his £ Angiospermen 
und Gymnospermen,’ Strasburger (79) makes the statement 
that it is the foremost of these two £ primordial cells ’ in the 
pollen-tube which becomes active in fertilization. In 1884, 
by a study of Picea excelsa , he confirmed Goroschankin’s ob- 
servation (’83) on Pinns as to the passage of both sperm-nuclei 
into the egg, but pointed out that only the one in advance 
fuses with the egg-nucleus. 
The same author in his work on the pollen of the Gymno- 
sperms (’92), in which he showed that Belajeffs observations 
(’91) on the development of the pollen-tube in Taxus baccata 
are in general true for other Gymnosperms, gave the results 
of observations on the germinating pollen of Picea excelsa. 
In the mature pollen-grain just before pollination he observed 
that the third prothallial cell or central cell 1 has already 
been divided into the stalk- and generative cells, the two other 
disintegrating prothallial cells being seen as two slit-like 
bodies. He also found that the generative cell divides into 
two sperm-cells before it passes down into the pollen-tube. 
In the following year Belajeff (’93), in his second paper on 
the pollen-tube of the Gymnosperms, described the further 
development of the pollen-tube in Picea excelsa. According 
to him the generative cell divides into two sperm-cells before 
it moves down into the pollen-tube ; the stalk-cell is broken 
down and only the nucleus follows the sperm-cells, finally 
1 I take the third prothallial cell as homologous to the central cell of the 
Pteridophytes, and the latter term is used throughout the paper. 
