164 BOTANICAL GAZETTE | SEPTEMBER 
would accord with the theory of DeBary that the Saprolegni- 
aceae evolved through the Peronosporaceae. 
The origin of the Peronosporaceae and Saprolegniaceae from 
lower forms is far from clear. Before the discovery of the 
multinucleate oosphere in 4. But, a relation to some type like 
Vaucheria seemed probable. In -Vaucheria many nuclei pass 
into the rudimentary oogonium, after which, as in A. candida, the 
superfluous nuclei retreat from the cytoplasmic region which is 
destined to become the oosphere. The essential difference is 
that in Vaucheria the formation of the wall at the base of the 
oogonium is delayed until the superfluous nuclei pass back into 
the parent branch. In the Peronosporaceae the wall is formed 
when the nuclei are still in the oogonium, thus prohibiting their 
retreat. The result must be either a multinucleate oosphere or 
a degeneration of superfluous nuclei. Oltmanns (1895, p. 414) 
has justly remarked that the condition in Vaucheria is very like 
that in Fucaceae, presenting only such differences as are neces- 
sitated by the presence of cell walls between the oogonium and 
the parent branch. The remark applies with equal force to the 
Albuginaceae, 
The probability that the ancestors of the Peronosporaceae 
and Saprolegniaceae had multinucleate oospheres removes these 
groups from Vaucheria-like forms. If there is any relationship 
the connection must have been at a time in the ancestry of 
Vaucheria before the abandonment of the multinucleate condi- 
tion of its oogonium. As Oltmanns (1895) says, the passage of 
many nuclei into the rudimentary oogonium in Vaucheria is 
most readily explicable on the assumption that it once produced 
many gametes instead of the one that is now habitually found, a 
view that must meet quite general acceptance, as may be seen 
from the recent paper of Blackman (1900) and the literature 
there cited. 
Mycologists generally acknowledge the close relationship 
between the Peronosporaceae, Saprolegniaceae, and Mucorineae. 
The presence of a multinucleate oosphere and antheridium, and 
" the fusion of two multinucleate masses of protoplasm, quite 
ES QSOS 
