138 Agnes Robertson. 
his discovery of the process of “ fertilisation ” preceding accidium 
formation . 1 He concludes that the Uredinese cannot he considered 
as a mere sub-division of the Basidiomycetes as in the well-known 
classification of Brefeld, but must be looked upon as a distinct and 
far more primitive group. He would rather regard the Basidio¬ 
mycetes as reduced apogamous forms of the Uredinere. 
Among the higher Cryptogams the most striking cytological 
feature which is useful in differentiating large groups is the 
character of the antherozoids (biciliate in the Bryophytes and 
Lycopods and multiciliate in the Ferns). Amongst the Phanero¬ 
gams as a rule the male cells have lost their power of locomotion, 
and therefore when ciliated sperms were discovered in the Cycads 
and Ginkgo it became clear that this was one of the most important 
points to be taken into account in placing these plants in a natural 
system. Ginkgo which had been assigned to the Taxaceae was 
removed into an alliance of its own, and the view that the Cycads 
were primitive Gymnosperms with a filicinean ancestry received 
confirmation. As regards fertilisation, the Conifers appear to have 
one common feature in which they differ from all other plants. 
The membrane of the egg nucleus is pushed in by the male nucleus, 
which finally comes to lie within it, both walls being intact. This 
was first described by Blackman 2 for Pinus. The large size and 
comparatively scanty chromatin of the egg nucleus seems also to 
be a characteristic feature of the group. There is another point 
in which I think one might expect to find constancy in related 
plants, but in which the Gymnosperms turn out to be highly 
variable, the behaviour, namely of the male cytoplasm. In Taxo- 
dium , 3 for instance, the whole male cell enters the egg; and the 
male cytoplasm forms a sheath round the fusion nucleus aud takes 
part in the formation of the embryo, whereas in Sequoia 4 the male 
nucleus slips from its cytoplasm aud enters the egg naked I Unless 
one imagines that these two plants have a radically different 
mechanism for the transmission of hereditary qualities, one is 
forced to conclude that it is the male nucleus alone that carries the 
1 V. H. Blackman. “ On the Fertilisation, Alternation of Genera¬ 
tions, and General Cytology of the Uredineae.” Annals of 
Botany. Vol. XVIII 1904, p. 323. 
1 V. H. Blackman. “On the Cytological Features of Fertilisation 
and Related Phenomena in Minis silvestris L.” Phil. Trans. 
Roy. Soc. Vol. 190b, 1898, p. 395. 
8 W. C. Coker. “ On the Gametophytes and Embryo of Taxo- 
dium.” Bot. Gaz., July, 1903. 
4 A. A. Lawson. The Gametophytes, Archegonia, Fertilisation 
and Embryo of Sequoia sempervirens. Annals of Botany, 
Vol. XVIII., 1904. 
