802 REPORT—1904. 
8, Exhibition of Micro-photographs of Freshwater Plankton. 
Ly Professor G. 8S. West. 
9. Exhibition af Kammatograph Photographs showing the Movements of 
Plants. By Mrs. D. H. Scorv. 
10. On the Artificial Formation of a New Race. By Professor G. KiEss. 
ll. The Present State of our Knowledge of the Cytology of the 
Cyanophycee. By Harotp WaceEr, F.2#.S. 
The Cyanophyces are in their cytological structure clearly marked off from all 
other groups of plants, with the possible exception of the Bacteria. The cell 
contents are differentiated into two distinct regions—a central colourless one (the 
nucleus) in which granules of various kinds occur, anda peripheral layer in which 
the colouring matters of the cell arecontained. According to the observations of 
Hegler, and more recently of Kohl, the nucleus undergoes a true process of 
karyolkinesis, and the colouring matters are contained in chromatophores, 
In a recent paper’ I have tried to show that the central body presents a 
sufficient number of nuclear characteristics to justify us in regarding it as a 
nucleus of a simple or rudimentary type, but I am not prepared to agree with 
Kohl that it produces true chromosomes and spindle fibres, or that it undergoes a 
normal process of karyokinesis similar to that which takes place in the higher 
plants. It seems to me to be a case of direct division, or at most a rudimentary 
karyokinesis. 
The structure of the resting nucleus is not unlike that of the higher plants, in 
that it possesses a network with chromatin granules; but any one who examines it 
attentively with high powers cannot help seeing that it differs in other respects, 
It does not possess a definite nuclear membrane, and there is no true nucleolus. 
The network structure is not so clearly defined as the normal nuclei; it gives one 
the impression that it is more of a vacuolisation than a true network. In fact, we 
may possibly regard the nucleus of the Cyanophycez as produced by the vacuoli- 
sation of the central region of the cell (Butschliand Chodat), and the accumulation 
of chromatin granules therein ; the fusion of the vacuoles and chromatin granules 
giving ultimately the appearance of a normal nuclear network. 
In addition to the chromatin granules, we find inside the nucleus granules of 
another kind, called by Butschli the ‘red granules.’ They were first of all seen 
by Zacharias, and called by him the ‘central substance.’ Their exact nature is 
not known, but they probably consist of some albuminous substance produced 
by the activity of the nucleus, and may represent either a reserve substance or a 
stage in the production of chromatin, or possibly a waste product. They contain 
phosphorus, and stain deeply in nuclear stains. 
Outside the nucleus, distributed irregularly in the cytoplasm or forming 
regular rows on the transverse walls, are the cyanophycin granules. These 
have characteristic reactions of their own, and are probably of the nature of albu- 
minous reserve substances. In some cases they give a reaction for phosphorus, and 
appear to stand in close relationship to the activities of the nucleus. 
The cell also contains glycogen, often in very considerable quantities. There 
is some evidence to show that this is produced as a result of assimilatiye 
activity. It is always abundant in a good light, and disappears in the dark. 
The colouring matters are contained in small granules in the peripheral 
cytoplasm. They are considered by Hegler and Kohl to represent the chromato- 
1 Proc. Roy. Soc. 72, 1903. 
