568 Trow. — On Fertilization in the Saprolegnieae. 
Van Hook, J. M. (’00) : Notes on the Division of the Cell and Nucleus in Liverworts. Bot. Gaz., 
vol. xxx. 
Wager, H., (’9.4) : On the Presence of Centrospheres in Fungi. Ann. of Botany, vol. viii. 
(’99) : The Sexuality of the Fungi. Ann. of Botany, vol. xiii. 
(’04) : The Nucleolus and Nuclear Division in the Root-apex of Phaseolus. Ann. of 
Botany, vol. xviii. 
Williams, J. Lloyd (’04) : Studies in the Dictyotaceae : I. The Cytology of the Tetrasporangium 
and the Germinating Tetraspore. Ann. of Botany, vol. xviii. 
Wilson, Edmund B. (’97) : The Cell in Development and Inheritance. New York, 1897. 
Wisselingh, C. van (’00) : Ueber Kerntheilung bei Spirogyra. Flora, Band lxxxvii. 
Zimmermann, A. (’96) : Die Morphologie und Physiologie des pflanzlichen Zellkernes. Jena, 1896. 
explanation of figures in plates xxxiv - xxxvi . 
Illustrating Dr. Trow’s paper on Fertilization in the Saprolegnieae. 
All the figures were drawn with the help of the camera lucida. The finer details were of 
course filled in by freehand after the main outlines had been traced under the camera. All the 
nuclei present in a section were drawn, each generally in median optical section. The details of the 
cytoplasm are represented somewhat diagrammatically, as it is impossible to represent more than one 
optical section in the same drawing. All the sections figured were 5 jw thick. Various stains were 
used. The drawings were all made under a magnification of about 1,250 diameters. Figures 1 to 
13, which represent sections of Achlya polyandra , have been reduced during the process of repro- 
duction to about 800 diameters. The remaining figures, which represent sections of Achlya De 
Baryana, have, with the exception of 14 and 15, not been reduced. Some of the drawings of the 
more typical nuclei, as well as other details in the various sections, have been enlarged and inserted 
separately in the plates in the neighbourhood* of the sections to which they belong, so that the 
structure might be more certainly demonstrated. 
Achlya polyandra. 
Fig. 1. A somewhat tangential section of an oogonium with the nuclei in metaphase and 
anaphase, a and b are apparently undergoing a second mitosis. 
Fig. 2. A nearly median section of an oogonium with the nuclei in mitosis. One nucleus 
showing the polar view of the nuclear-plate. 
Fig. 3. A median section of an oogonium, and a section of an antheridium with the nuclei in 
mitosis. One nucleus has a typical spindle and nuclear-plate. 
Fig. 4. One section (the fourth of nine) through an oogonium which contained four origins, each 
uninucleate. Three origins shown, each with a functional nucleus (/.».) and degenerate nuclei ( d ’ n.). 
Fig. 5. Section of an oogonium (the first of eleven examined) which contained seven uninucleate 
oospheres. A doubtful centrosome is shown at a. 
Fig. 6. The third section of the same oogonium (as in Fig. 5). 
Fig. 7. The fifth section of a series of five sections through an oogonium which contained five 
binucleate oospores, a had two nuclei in the fourth section and b had one. Two other oogonia on 
the same slide had eight and six binucleate oospores in series of seven and eight sections re- 
spectively. 
Fig. 8. A young oospore. The two nuclei in contact by their anterior pointed ends, where is to 
be seen a pair of deeply stained granules. 
Fig. 9. One of four half-matured oospores present in a small oogonium, all of which were 
uninucleate. 
Fig. 10. One of four sections of an oogonium which contained three uninucleate oospores. 
The oospore wall well developed and as thick as the wall of the oogonium. 
Figs. 11 and 12. Sections (two of five) of an oogonium which contained two oospores only. 
The fertilization-tube in eleven is anomalous, the normal tube being shown in twelve. The swollen 
fertilization-tube is likewise, so far as my experience goes, a unique anomaly. 
Fig. 13. Section of an oosphere with fertilization-tube attached to it, the protoplasm in both 
being perfectly continuous. 
