332 Phillips on a Comparative Study of the 
96. Zopf.—‘‘Zur Morphologie der Spaltpflanzen.” Leipzig, 1883. 
97. Zopf.—‘“Weitere Stiitzen fiir meine Theorie von der Inconstanz der 
Spaltalgen Tolypothrix amphibica, Zopf.’ Ber. d. deut. bot. 
Gesell., Bd. i, 1883. 
98. Zukal—‘Beitrage zur Kenntniss der Cyanophyceen.” Oesterr. bot. 
Zeitschr., 1894. (Also reviewed in Bot. Cent., for 1895.) 
99. Zukal—‘“Ueber den Zellinhalt der Schizophyten.” Sitzungsberichte 
der K.-Akad. d. Wiss. in Wien, Bd. ci, 1892. 
100. Zukal.—‘Ueber den Zellinhalt der Schizophyten.” Ber. d. deut. 
bot. Gesell., Bd. x, 1892. 
tor. Zukal.—‘Neue Beobachtungen ueber einige Cyanophyceen.” Ber. 
d. deut. bot. Gesell., Bd. xii, 1894. 
102. Zukal.—‘Zur Frage ueber den Zellinhalt der Cyanophyceen.” Ber. 
d. deut. bot. Gesell., Bd. xii, 1894. 
103. Zukal.—‘Beitrage zur Kenntniss der Cyanophyceen.” O6esterr. bot. 
Zeitschr., 1894. 
(11) EXPLANATION OF PLATES. 
PLATE XXIII. 
Fig. 1. Cell of Oscillaria showing the chromatin vesicles of the central 
body in the resting condition. Also shows the cilia on each side 
wall. 
Fig. 2. Diffuse net-spireme stage of division in Oscillarta. 
Fig. 3. Net-spireme drawn to the equator of the cell of Oscillaria. 
Fig. 4. Net-spireme constricting and division walls of consolidating 
microsomata growing inward from the side walls. 
Fig. 5. Division of cell of Oscillaria completed. 
Fig. 6. Cell of Oscillaria with diffused nucleus, from which the net- 
spireme of Fig. 2 will form. 
Fig. 7. Cell of Oscillaria showing the beginning of the collar-like 
ingrowth, which will form the division wall. Ingrowth composed 
of microsomata of cellulose. 
Fig. 8. Spireme forming into segments or chromosomes in Oscillaria. 
Fig. 9. Same as Fig. 8, but with chromosomes and spindle fully 
formed. 
Fig. 10. Same as Fig. 9, but with the chromosomes dividing. 
Fig. 11. Cell of Oscillaria in which two large chromosomes have 
formed. 
Fig. 12. Same as Fig. 10, but with heavier chromosomes. 
Fig. 13. Chromosomes shown in Fig. 11 are here shown dividing. 
Fig. 14. Division completed. 
Figs. 15-20. Successive division stages in O. Froehlichii. 
Fig. 21. Spireme of Oscillaria much enlarged. 
