Pinus silvestris. 
27 
By May 26 the pollen- tube had usually reached the em- 
bryo-sac. In many cases fertilization was already accom- 
plished and some divisions of the fertilized oosphere had 
occurred. When the pollen-tube reaches the oosphere, not 
only do the sexual nuclei pass into the latter, but even the 
two asexual nuclei also ; so that in no case was either the 
nucleus of the pollen-tube or that of the stalk-cell observed to 
remain behind, and it was possible in very many cases to 
find them in the protoplasm of the oosphere (Figs. 13, 14). 
Along with these nuclei much of the protoplasm of the 
pollen-tube passes into the oosphere carrying with it 
numerous grains of starch, so that one often finds sections 
presenting the appearance shown in Fig. 15, where the nuclei 
are followed by a tail of protoplasm, or in Fig. 16, where 
their track is marked out by the starch-grains which have 
come from the pollen-tube, for before the pollen-tube reaches 
the oosphere, the latter contains no starch. These nuclei 
persist for a considerable time and are to be found in the 
protoplasm of the oospore after its nucleus has divided several 
times (Figs. 16, 17). In no case did I find the nuclei in 
the act of passing from the pollen-tube into the oosphere. 
The apex of the pollen-tube is often seen to be furnished 
with a deep pit, which may appear very like a perforation 
(Fig. 18). I am, however, fortunate to be able to quote 
Prof. Strasburger’s opinion on this point. He was kind 
enough to examine several preparations, such as is figured in 
Fig. 18, and he regards them as showing examples of the 
pit first described by Hofmeister 1 and afterwards by Schacht 2 , 
and by himself 3 . 
1 Pringsheim’s Jahrb. fur Wiss. Bot., Bd. I, p. 71. 
2 Sitzgsber. d. Niederrh. Gesells. fur Natur- und Heilkunde zu Bonn, 1864. III. 
Folge, Bd. I, p. 94. 
3 Befruchtung bei den Coniferen, 1869, pp. 11, 13, 14. Since the above was 
written, I find that G. Karsten (Cohn’s Beitrage zur Biologie der Pflanzen, 
Bd. VI, Heft 3, p. 367) describes and figures the pollen-tube of Gnelum R umphi- 
anum and of G. ovalifolium at the moment of fertilization, showing that it is 
perforated at the apex and that through this perforation its contents pass into the 
embryo-sac. 
