F. E. Fritsch. 
2 I 
m 
Fig. 25. Longitudinal section of a proembryo with six cells open above and 
one tip cell. The nucleus in the upper part of the archegonium is 
probably the second male nucleus, or one of its products of division. 
September 12th. ( x 400.) 
Fig. 26. Longitudinal hand section of a proembryo in which the rosette cells, 
suspensors and tip cells are already organised, cf. Fig. 29. September 
19th. (x 400). 
Fig. 27. Longitudinal section of a proembryo whose suspensors have begun 
to elongate, cf. Fig 28. October 19. (x 400). 
Fig. 28. Diagrammatic longitudinal section of a seed without its arillus. cf. 
Fig. 27. October 19th. (x 28). 
Fig. 29. Shoot bearing a pair of seeds, cf. fig. 26. September 19th. (Nat. 
Size). 
Fig. 29a. Seed of same date as fig. 29, surrounded by its four bracts, (x 2) r 
Fig. 29b. Bracts removed, seed with arillus exposed, (x 2). 
Fig. 29c. Arillus removed, seed with integument exposed, (x 2.) 
STUDIES ON CYANOPHYCEAE. 
By F. E. Fritsch, B.Sc., Ph. D., F.L.S. 
III. —-Some Points in the Reproduction of Anabaena. 1 
[With Plate X.] 
NDEPENDENTLY of the reproduction of the Cyanophyceae 
by means of hormogonia, the sole certain method known to us 
is that by means of spores and gonidia. Spores are now known in 
a considerable number of blue-green genera, as will be seen by 
reference to Brand’s recent synopsis of them,'- but a large number 
of forms remain, in which they have not yet been found, nor are 
the details of their formation and germination fully known in those 
genera, where their occurrence is an established fact. The most 
important contributions from this point of view are due to Borzi, who 
in his “Notealia Morfologiae Biologia delle Alghe Ficochromacee,” 
1 No. 2 of this series, dealing with the structure of the investment 
and the spore-development of some Cyanophyceae, is about 
to appear in the Beihefte zum Botanischen Centralblatt (Bd. 
18, Abt. I., Heft 2), pp. 30-50 and Tab. VII. 
2 cf. Brand in Beihefte z. Botan. Centralbl., Bd. xv., Heft 1, 1903, 
pp. 37 and 38. 
