33 2 Phillips on a Comparative Study of the 



96. Zopf. — "Zur Morphologie der Spaltpflanzen." Leipzig, 1883. 



97. Zopf. — "Weitere Stutzen fiir meine Theorie von der Inconstanz der 



Spaltalgeii Tolypothrix amphibica, Zopf." Ber. d. deut. bot. 

 Gesel!,, 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 Schizophjlen." Ber. d. deut. 



bot. Gesell., Bd. x, 1892. 



101. 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." Oesterr. bot. 



Zeitschr., 1894. 



(II) EXPLANATION OF PLATES. 



Plate XXIH. 



Fig. I. 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. Diiifuse net-spirenie stage of division in Oscillaria. 

 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 tlie 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. II. 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 mucli enlarged. 



