234 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
whether in the center or later at the periphery ; this association for 
so long a period, indicates that they mutually attract each other, a 
phenomenon that suggests them to be sexual rather than vegetative 
nuclei. (5) During this period they make a conspicuous growth in 
size (pi. 15, figs. 35, 37), a common phenomenon of sexual nuclei. 
(6) Nuclear fusion is delayed for a considerable time in some related 
forms: Basidiobolus ranarum (Fairchild, ’ 97 ), Monoblepharis (Lag- 
erheim, :00), Peronospora parasitica (Wager, :00), and Polyphagus 
euglenae (Wager, ’ 99 ). 
Development of the Oospore. 
Attention has been called to the fact that the central ooplasm 
begins to spread out into the oospore soon after the sperm nucleus 
is introduced. When the greater portion of this has disappeared 
from the interior and the two nuclei are near the center of the 
oospore, the latter begins laying down a wall on the inside of the 
periplasmic wall (pi. 14, fig. 25—28). As this wall grows in thick¬ 
ness the coarser vacuoles become larger and fewer. This massing 
of the oleagenous substance with which the vacuoles are filled, con¬ 
tinues until in most cases one large, conspicuous, yellow globule is 
formed in the center of the oospore (pi. 14, fig. 31). In some cases,, 
the oleagenous substance is collected into several globules even in 
what otherwise appear to be equally mature oospores (pi. 14, fig. 30). 
In the latter case, the nuclei are centrally placed while in the former^ 
which is the more common, they are of course, lateral. Figure 29 
(plate 14) which in this section shows no globule, has a conspicuous,, 
central one in the succeeding sections. In many cases, particularly 
in young oospores, there are small oil globules occupying the central 
region of much larger alveolae, suggesting that all but the remnants 
of these globules had been dissolved by the various reagents through 
which the sections were passed (pi. 14, fig. 25). In other cases, con¬ 
spicuous cavities may be seen in the globules themselves indicating 
that they are not of the same chemical composition throughout. 
Figures 30 and 31 (plate 14) represent oospores as old as were 
met with in the course of the investigation. Scores of these, each 
binucleate, were found. The two walls are, at this time, distinct; 
the outer is thin ami takes the gentian deeply, the inner is thick and 
stains feebly with gentian. These two walls are present on the 
