898 
PHENOMENA OF SEXUAL REPRODUCTION. 
after it is extruded it is set in rotation by the attached antherozoids ; it usually 
remains enclosed in the mother-cell that produces it (the oogonium of Algae and 
Fungi, the archegonium of Muscinese, Vascular Cryptogams, and Gymnosperms, 
and the embryo-sac of Angiosperms), where it awaits fertilisation. While the male 
cell loses during the union its character as an individual cell, the oosphere is 
rendered capable of a more complete individual existence, which is first indicated 
by the invariable formation of a wall of cellulose, even when the oosphere results 
simply from the contraction of the protoplasm of an oogonium and still remains 
enclosed in its cell- wall, as in (Edogonium and Vaucheria. In this respect the 
zygospore of Conjugatae and Mucorini behaves also like a fertilised oosphere 
or oospore. 
The male cell is more variable in its form and in its behaviour in the process 
of fertilisation. It always n:\oves to the oosphere which remains at rest ; in the 
riorideae it is carried passively by the water ; in the Fucaceae, in Vaucheria, (Edogo- 
nium, and other Algae, in all Characeae, Muscineae, and Vascular Cryptogams, it 
swims actively. In other cases the male organ becomes attached in its growth to 
the female organ, as in the antheridial branches (pollinodia) of some Saprolegnieae 
and of some Ascomycetes, and the pollen-tube of Phanerogams. The great variety of 
form of the male cell becomes especially conspicuous if we compare the roundish 
swarm-spore-like antherozoids of (Edogonium and ColeochcBte with the filiform anther- 
ozoids of Characeae, Muscineae, and Vascular Cryptogams, and with the rounded 
non-motile antherozoids of the Florideae which (like the spermatia of Lichens) possess 
a cell-wall. The form is in each case evidently adapted to produce the right 
kind of motion in order to convey the fertilising substance to the female organ in 
a manner in harmony with its structure ; while in the fertilisation of the latter the 
quality of the substance only is concerned. 
According to the present state of our knowledge it may be assumed that 
fertilisation essentially consists in a union of protoplasm and nuclear substance 
derived from the male organ with protoplasm and nuclear substance of the female 
organ. In conjugation this union is brought about by the coalescence of the two 
conjugating cells. In the fertilisation of (Edogonium and Vaucheria, the entrance 
of the antherozoid into the protoplasm of the oosphere and its absorption in it 
has been observed by Pringsheim. The antherozoids of Muscineae and Ferns 
were observed by Hofmeister, and those of Marsilia by Hanstein, to enter the 
archegonium, those of Ferns by Strasburger to penetrate to the oosphere itself. 
It must therefore be inferred from analogy that in Phanerogams a union ^ takes 
place of some substance contained in the pollen-tube with the oosphere ; and in 
certain Ascomycetes of the contents of the pollinodium with those of the asco- 
gonium. It would be impossible otherwise to explain how in these cases the 
mere contact of the often thick-walled pollen-tube with the embryo-sac, or of 
the pollinodium with the ascogonium, can effect fertilisation, while in the former 
cases such a complete coalescence of the male and female cells is necessary for 
this purpose. 
^ [See pp. 524 and 584. J 
