F ertilization of Pinus silvestris 1 
BY 
HENRY H. DIXON, B.A. 
Assistant to the Professor of Botany in Trinity College , Dublin. 
With Plates III, IV, and V. 
REVIOUSLY to the appearance of Belajeff’s paper in 
JL 1891 on the behaviour of the nuclei of the pollen-grains 
of Taxus baccata 2 , it was believed that the nucleus of the 
pollen-tube of the Gymnosperms was the male sexual nucleus, 
and that the cell-group formed in the pollen-grain opposite the 
point of exit of the pollen-tube was composed of two or more 
asexual cells corresponding to the sterile cell cut off in 
the microspore of the Selaginelleae. Prof. Strasburger had 
already shown 3 that the nucleus of the pollen-tube of 
Angiosperms was asexual, and that although it passed into 
the tube it eventually disintegrated and took no part in 
fertilization ; while the nucleus of one of the cells originally 
behind the nucleus of the pollen-tube performed the function 
of fertilization. Belajeff, in the paper already referred to, 
showed that the nuclei of the pollen-grains of Taxus behaved 
in a manner resembling in its most important points that of 
the Angiosperms: i. e. that the nucleus of the pollen-tube is 
asexual and that fertilization takes place by the union of one 
of the nuclei of the two cells resulting from the division of one 
1 This research was carried out in the Botanisches Institut of the University 
of Bonn, at the suggestion and under the supervision of Professor Strasburger, 
who not only supplied me the necessary material, but also was good enough 
to give me the benefit of his great experience. 
2 Berichte der Deutschen botanischen Gesellschaft, Bd. IX, p. 280. 
3 Befruchtungsvorgang bei den Phanerogamen. Jena, 1884. 
[Annals of Botany, Vol. VIII. No. XXIX. March, 1894.] 
