304 Trow. — Observations on the Biology and 
Provisionally, at any rate, Strasburger’s view may be adopted, 
and efforts should be made to extend our knowledge of the 
cytology of the gametangia and gametes in the sexual 
Thallophytes. It is probable that gameto-nuclei are much 
more susceptible to degenerative changes than vegetative 
nuclei. If so, the advantage of all the nuclei retaining their 
powers of division, rather than one only, is clear. The 
daughter-nuclei are more readily digested and absorbed. 
Three types of fertilization have been described as occurring 
in the Peronosporaceae, but now that Fisch’s type (. Pythium ) 
falls to the ground, there remain but two — the normal one 
common to most plants, and that described so fully by 
Stevens for Cystopus Bliti and styled concisely by Wager 
(’00), 4 multiple nuclear fusions in pairs.’ 
Davis has endeavoured to harmonize these widely divergent 
types by deriving the Oomycetes from Zygomycete-like 
ancestors. It is perfectly easy to construct a subjective 
phylogeny in this way. Ideas of this kind are, however, 
of value chiefly in proportion to the amount of objectivity 
which they represent. It is just as easy to construct a 
phylogeny without reference to the Zygomycetes, which, 
though to a great extent theoretical, has a considerable 
foundation of fact. 
We have in Monoblepharis a Fungus in which all the repro- 
ductive organs are still so much alike (sporangium-like) that 
their homology is at once apparent. Had the oogonium a 
number of oospores like that of Sphaeroplea, the resemblances 
would be more striking still. Saprolegnia offers little advance 
on the condition seen in Monoblepharis . The oogonia and 
sporangia are very similar. The numerous oospheres differ 
from the spores in size, owing no doubt to the fact that in 
their formation nuclei have been absorbed and digested. The 
successful nuclei preside over an unusual amount of cytoplasm. 
The antheridia are however reduced. The fewer the eggs, 
the smaller should the antheridia be. The reduction of the 
antheridium obviously goes hand in hand with the increase in 
size and diminution in number of the oospheres. Zooidiogamy 
