1904] DAVIS—OOGENESIS IN VAUCHERIA gt 
fewer eggs are developed than the number of gamete nuclei, but 
before a habit of nuclear degeneration has become fully established. 
It is altogether probable that the extra nuclei in the eggs of the var. 
Braunii do eventually break down. 
Besides Sphaeroplea, it is very important that we know the pro- 
cesses of oogenesis in Monoblepharis, since this form has a structure 
with many points of resemblance to the algae on the one hand and the - 
groups of Saprolegniales and Peronosporales on the other. LAGER- 
HEIM (’oo) states that a single large nucleus enters the developing 
oogonium to become the gamete nucleus of the egg. Such a history 
is not in sympathy with oogenesis in Vaucheria and the Peronosporales 
or Saprolegniales, nor is it in sympathy with his own description of 
spermatogenesis in Monoblepharis. The antheridium contains many 
nuclei, each of which enters into the development ofa sperm as in 
Vaucheria. The author cannot but think that LAGERHEIN’s account 
of oogenesis is incorrect, or else that the conditions here are very 
exceptional. It seems very probable that Monoblepharis and perhaps 
some of the forms in the Leptomitaceae are closely related to Vau- 
cheria. 
The problem of the relationship of the events of oogenesis in the 
Saprolegniales and Peronosporales to Vaucheria may be stated as 
follows. Have the conditions in these groups been developed directly 
from the relatively simple process illustrated by Vaucheria, or are 
there peculiarities in these two groups that would make necessary 
their derivation from more generalized types ? 
The Saprolegniales present conditions that superficially bear a 
very close resemblanee to Sphaeroplea, 7. e., there are several eggs 
in the oogonium. But these eggs are differentiated around ‘coeno- 
centra which determine the survival of a limited number of nuclei, 
while the great majority break down. There are fundamental 
differences between these events and oogenesis in Sphaeroplea, 
unless later studies should establish nuclear degeneration in the 
latter type. It would not be difficult to conceive the development 
of several metabolic centers in a large gametangium of one of the 
Siphonales, and the survival of several nuclei to form as many eggs 
which would give a condition exactly like that of Saprolegnia. So 
the present investigation with the discovery of a multinucleate oogo- 
