258 BOTANICAL GAZETTE [OCTOBER 
—— 1899: Observations on the biology and cytology of a new variety of 
Achlya Americana. Ann. Bot. 13: 131-179. 
VERWORN, 1897: Allgemeine Pigaiskigic. 
WAGER, 1896: On the structure and eduction of Cystopus candidus. 
Ann. Bot. 10: 295-342 
—  Igoo: On the fextilitation of Peronospora parasitica. Ann, Bot. 
: O77 a 
ILSON, 1900: The cell in development and inheritance. 
ZALEWSKI, 1883: Zur Kenntniss der Gattung Cystopus. Bot. Centralb. 
15: 1-10. 
ZIMMERMANN, 1896: Die Morphologie und Physiologie des pflanzlichen 
Zellkernes. 
ZopF, 1890: Die Pilze in morphologischer, physiologischer, biologischer 
und systematischer Beziehung. Schenk’s Handbuch der Botanik 
4:271-756. 
EXPLANATION OF PLATES I-IV. 
All figures are from material killed in chrom-acetic acid and stained 
with Flemming’s triple stain. The figures were sketched with the aid of an 
Abbé camera, using the Leitz ,, objective, aperture 1.30, and oculars I 
and 4. 
PLATE I, Albugo Portulacae. 
Fig. 1. Early stage in massing of Seca nuclei in advanced 
sagt receptive papilla prominent. X 
. 2. Later stage in oogenesis; nuclei near metaphase ; ooplasm and 
perp of very different structure, but not sharply delimited. x 857- 
. Zonation ; nuclei in metaphase; ooplasm and periplasm sharply 
aie as. coenocentrum prominent, consisting of a loosely vacuolate 
center srecdonabid 2 a denser, slightly granular region which stains darker 
with the orange G. ve 
Fig. 4. ena later than fig. 7, primary oospheric nuclei entering 
oosphere ; ooplasm and periplasm sharply delimited; ooplasm typically 
alveolar, staining very lightly with orange G; periplasm staining densely 
with gentian violet, filar in structure; three reentering nuclei show each a 
very weak but distinct polar ray; coenocentrum has disappeared. X 857. 
Fic. 5. Primary oospheric nuclei before second division; receptive 
papilla very prominent; later than jig. 4. X 857 
Fic. 6. Receptive papilla open; oospheric nuclei in second mitosis. 
x oe 
G. 7. Antheridial ‘tube in oblique section showing many nuclei and no 
ees oospheric nuclei in second mitosis. x 857. 
Fig. 8. Antheridial tube in section slightly st te sperm nuclei numer 
ous, elongated ; stage slightly older than in fig. 7. X 
