1899] THE COMPOUND OOSPHERE OF ALBUGO BLITI 157 
of the resulting condition is presented in fig. 64. The outer region 
ofthe oogonium, the rudimentary periplasm, is coarsely. vacuo- 
late, presenting a conspicuous contrast to the dense central mass. 
Along the boundary between these two regions are gathered most 
oi the nuclei (fig. 6g). 
The next stage in the differentiation of the oosphere is. con- 
spicuous and clearly characterized. It ends in producing a dis- 
tinct differentiation between the oosphere and the periplasm 
“fg. 65). This condition is brought about primarily by the mar- 
shaling of the nuclei into an oval or an irregular hollow sphere; 
a section of which is shown in jig. 65, while a somewhat earlier 
Stage is to be seen in Jig. 64. Both figures illustrate the one 
important fact that all or nearly al] of the nuclei are at the 
boundary of the central dense mass. The latter figure in addition 
shows that there is a sharp line of demarcation between the 
3 lasm and periplasm. There are usually a few scattered nuclei 
1 the periplasm, and occasionally one finds a nucleus in the 
Sosphere that has not passed out as rapidly as the others. 
Important changes occur in the cytoplasm while the nuclei are 
‘vanging themselves into a hollow sphere. At the beginning of 
this process the region that is to become periplasm is coarsely 
“chap in marked contrast to the dense cytoplasm of the 
meet ut the two regions blend gradually together where they 
(Jigs. 62, 64). Later when the hollow sphere of nuclei 
ome ty regular in outline dense granular cytoplasm ig 
ie : gap and between the nuclei (figs. 65, 68, 69). 
differentiated : er of the rudimentary periplasm also becomes 
region of th peo a film more densely granulated than any other 
sphere oC and finally determines the limit of the 
Critical ae fre is not yet an organized wall, and the most 
: y Teveals nothing more than a dense film of proto- 
7oNation, * 1S convenient to call this condition the stage of 
The Position 
Vents lead 
ading to 
"RQ this ¢ 
of the stage of zonation in the sequence of 
_to the differentiation of the oosphere is clear. 
endition comes the characteristic and sharp limitation 
