88 BOTANICAL GAZETTE [AUGUST 
that any nuclei escape through the boundary into the periplasm, 
but they are seen in the ooplasm in all stages of degeneration. 
The coenocentrum in A. Tragopogonis, as in A. Buti and A. 
Portulacae, makes its appearance when the central mass of 
ooplasm is formed just before zonation (figs. 27, 28). It first 
consists of an area of cytoplasm which takes the orange G with 
great avidity, while the neighboring cytoplasm stains deeply 
with the gentian violet. A trifle later than zonation the coeno- 
centrum is very highly developed, and appears in section as 
several zones of cytoplasm differing in density and stain reac- 
tion. The innermost area is coarsely vacuolate, and stains 
lightly with orange G. This region is surrounded by a narrower 
zone of dense granular cytoplasm, which is in turn encompassed 
by a less dense zone, and this finally by a broad zone of cyto- 
plasm which stains more deeply with gentian violet. This con- 
dition is not greatly changed at the time of entrance of the 
primary oospheric nuclei represented in fig. 30. In later stages 
the outer zones are lost, and the innermost region assumes a 
characteristic homogeneous oily appearance and is quite spherical 
(fig. 31). About the time of the second mitosis the innermost 
region, all that remains of the coenocentrum, loses its clear 
appearance and becomes coarsely granular (fig. 32), and in its 
stain reaction shows the probability of nuclear contents. The 
vacuolate area seen in the center of very young coenocentra 
(fig. 30) is probably a reservoir for the reception of foods that 
are elaborated by the- surrounding (presumably zymogenic) 
zone, which is in turn encompassed by typical trophoplasm. 
As the coenocentrum becomes older, these vacuoles, or rather 
globules of food stuffs in the protoplasm coalesce, and form 
the one central globule, which at first has a clear oily appear- 
ance (fig. 37), although it is not a true oil. 
The coenocentrum possesses an attraction for the nuclei 
similar to that noted by Wager (1900) in Peronospora parasitica. 
Nuclei in greatly elongated condition, apparently moving 
toward the coenocentrum, give sufficient evidence of this (jigs. 
30,31). As a result, several nuclei come into actual contact 
