. 
1904] DAVIS—OOGENESIS IN VAUCHERIA 93 
with the female. All of these antheridia behave in the same manner 
whether there are one or many functional gamete nuclei. This 
condition must have been closely associated in its origin with the 
suppression of the habit of forming pores for the discharge of zoo- 
spores or motile gametes. 
We do not know enough about the pore-forming activity in zoo- 
sporangia and gametangia to understand how readily it may be 
given up, and whether its presence or absence is of great morphological 
importance. The activity is absent in the gametangia of the Muco- 
rales, Saprolegniales, and Peronosporales, but present in the spor- 
angia of the Saprolegniales and most Peronosporales (conidia which 
produce zoospores), although lacking in some forms (Peronospora 
and certain species of Pythium) whose conidia germinate by a tube. 
The sporangia of the molds may have at one time developed zoo- 
spores, but there is at present no hint of such possible activities, 
except a general agreement in the processes of protoplasmic cleavage 
by furrows with spore-formation in such zoosporangia as have been 
studied (Hydrodictyon, Saprolegia, etc.). 
If the suppression of the pore-forming activity may take place 
readily after some slight change in life-habits, there would seem to 
be no great difficulty in relating the processes of oogenesis in Sapro- 
legnia and the Peronosporales rather closely to Vaucheria or relatives 
of Vaucheria. But if pore-formation may be given up only under 
exceptional conditions and infrequently, then it becomes very ques- 
tionable whether there can be a close relation to Vaucheria, and we 
must look to another line of ancestry for the Saprolegniales and Per- 
onosporales. The author thinks the latter condition at least quite 
possible and deserving of further consideration. 
Such an ancestry for the Saprolegniales and Peronosporales 
would naturally be sought through simpler conditions, somewhat 
like those illustrated in the Mucorales whose gametangia are coeno- 
gametes. It is scarcely conceivable that the molds are very closely 
related to the first two groups, but their coenogametes illustrate 
such well-defined sexual conditions that they naturally enter into the 
discussion. It is possible that groups with coenogametes like those 
of the molds might gradually differentiate such structures until they 
would finally become male and female sexual organs. The female 
