226 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
that the male nucleus had entered the egg at an acute angle to this 
place and is now moving in response to a second force. 
The fate of the structure remains to be discussed. Only one 
writer, Davis (:00), has furnished any details on this point. In 
Albugo Candida , whose oospheres have a well differentiated coeno- 
centrum, it has two methods of dissolution: “The structure may 
increase in size, the outline becoming vague, until there is finally 
present an irregular mass of protoplasm usually surrounding the 
fusion nucleus. Or the coenocentrum may fragment into several 
portions, as is shown in fig. 7, and these later swell and merge into 
an unorganized granular protoplasmic mass.” 
My own observations show that soon after the sperm nucleus 
enters the mass, this mass begins to spread out into the peripheral 
cytoplasm of the oospore. It will be recalled that when the sperm 
nucleus is introduced the central region is sharply differentiated 
from the remaining ooplasm which is coarsely vacuolate. Figures 
19, 21 (plate 13), 24 (plate 14), 35 and 36 (plate 15) represent 
sections in which the fine meshed strands are radiating out into the 
peripheral region. As this movement continues, the coarse meshed 
portions become more and more restricted by the fine meshed sur¬ 
rounding areas until only isolated large vacuoles remain (pi. 13, 
fig. 21 ; pi. 14, figs. 24, 26, 31). In this way the great mass of cyto¬ 
plasm of the developing oospore becomes fine meshed. 
The central mass then persists as a definite structure until after 
both nuclei enter it. Immediately afterwards, although the nuclei 
may still be some distance apart, it begins to radiate out into the 
peripheral ooplasm in a characteristic way. Such a highly differ¬ 
entiated region arising as it does, gradually, during almost the entire 
development of the oogonium, taking a definite form as the other 
parts of the oogonium are differentiated, reaching its highest devel¬ 
opment at the time the sexual nuclei enter it, and finally becoming 
less prominent immediately afterward and before the nuclei fuse or, 
as in some cases, are even near each other, adds to the previously 
published evidence that one important function of this differentiated 
region is to bring the sexual nuclei into the interior of the oosphere. 
The peripheral cells .— As the oosphere is cut off from the peri¬ 
plasm the latter is divided into a large number of cells by the radial 
division of the intervacuolar strands. In this respect Araiospora is 
again unlike other known Phycomycetes. Its nearest relatives that 
