454 THE AMERICAN NATURALIST. (Vow. XXXIX. 
phytes in which a reduction of the chromosomes is reported just 
previous to or during gametogenesis. The best known case is 
Fucus since this type has been studied by three investigators : 
Farmer and Williams (98) and Strasburger ('97a). They agree 
in describing the nuclear figure that differentiates the oógonium 
from the stalk cell as exhibiting a large number of chromosomes 
(28 or 30) while the three mitoses within the oógonium, which 
give rise to the eight eggs, present only one half that number 
(14 or 15). Apparently there is a reduction by one half just 
before the mitoses in the oógonium. Since there is no sporo- 
phyte generation in Fucus itis of course difficult to compare 
these conditions with those in higher plants, but, as will be 
explained later, there are some reasons why we should not 
expect to find reduction phenomena at gametogenesis in any 
thallophyte. 
Reduction phenomena at gametogenesis have also been sug- 
gested for various types of the Peronosporales and Saproleg- 
niales but not, however, in exactly the same way as in Fucus. 
There are always, as far as is known, one or two mitoses within 
the oógonium before the gamete nuclei are organized and it has 
been held that these are reduction divisions by Rosenberg for the 
Peronosporales and by Trow for the Saprolegniales. Rosenberg 
(: 03b) described for the oógonium of Plasmopara a condition of 
synapsis in the nuclei preceding the two mitoses and compared 
this sequence with the events of sporogenesis in higher plants 
in which the two divisions within the spore mother-cell are pre- 
ceded by a period of synapsis. Rosenberg did not determine the 
number of chromosomes in the vegetative nuclei so that he has 
no positive evidence of reduction in the oógonia. With respect 
to the two mitoses and the preliminary synapsis I have already 
pointed out in criticism of Rosenberg's studies (Bor. Gaz., vol. 
36, p. 154. 1903) that the number of mitoses is variable in the 
oógonia of the Peronosporales and Saprolegniales and apparently 
entirely absent in the species of Vaucheria studied by myself 
(Davis, :04a). Also, the phenomenon of synapsis, which is 
easily recognized in the large nuclei of the spore mother-cell, 
would be difficult to establish in the small nuclei within the 
oögonia of the forms mentioned above. Nuclei can be found 
