ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
307 
coalesce into a “ chromatin-sphere,” round which is formed the new 
nuclear membrane. 
The nucleole is absorbed before metaphasis ; in the later prophases 
the nucleus contains simply chromatin-bodies ; the new nucleoles are 
clearly seen only after the second division of the nucleus. The union of 
the chromatin into a more or less characteristic body corresponds closely 
to the process in Spirogyra. 
Reproduction of Dictyota.* — According to Mr. J. LI. Williams, the 
tetraspores of Dictyota dichotoma are produced throughout the season ; 
the sori are formed during neap-tides, and the spores are liberated during 
or immediately after the highest spring-tides. When liberated, the 
oospheres are not invested with walls ; in this condition they strongly 
attract the antherozoids. If not fertilised, they lose the power of attract- 
ing antherozoids, form walls, and germinate. The author believes that 
the factor which determines the maturation and liberation of the sexual 
cells, and the fertilisation of the oospheres, is the amount of illumination 
to which the plants are subjected. 
Agardh’s Analecta Algologica.f — The 4th “ Continuatio ” of this 
important contribution to Algology treats chiefly of the following sub- 
jects : — The structure and affinity of Cystoclonium, which is referred to 
the order Dumontiaceae of Florideae ; The structure and affinity of 
Spyridia, with a monograph of the species ; the author regarding the 
genus as exhibiting greater affinity with the Rhodomeleae than with the 
Ceramiaceae ; The structure and affinity of Furcellaria, presenting no close 
affinity with any other form ; On the fertile portions of Eydrolapathum ; On 
Ballia liamulosa ; The genus Thamnocarpus ; The species of Microcladia ; 
Erythroclonium Miilleri ; Certain species of Delesseria ; The structure of 
the fruit of Zanardinia ; The genus Wiododactylis ; The variations in the 
structure of Mychodea ; Endogenea, genus or subgenus ; The species of 
Dictymenia ; The characters of Bostrychea, with a synopsis of the species ; 
The fructiferous organs of Cliftonia ; Variations in the structure of Nereia 
(Fucoideae); New species of Myriodesma. 
Sexuality of the Ectocarpaceae.J — Herr F. Oltmanns now admits, 
in all essential points, the accuracy of Berthold’s account of the conju- 
gation of gametes in Edocarpus siliculosus ; although the process appears 
to occur only under peculiar conditions not yet accurately determined. 
The fusion may commence at any spot of the two gametes ; the nuclei 
eventually coalescing completely ; the chromatophores do not unite. 
The swarming bodies are of two kinds, larger and smaller ; conjugation 
takes place only between the smaller ones ; the larger ones germinate 
directly. The reproductive bodies of Edocarpus and Tilopteris may be 
classified as follows : — 
I. Unilocular sporanges, which form 
a. Normal zoospores. 
b. Aplanospores. 
c. Monospores (Akinetes) (?). 
* Ann. of Bot., xii. (1898) pp. 559-60. 
t Acta Univ. Lund, xxxiii. (1897) 10b' pp. and 2 pis. Cf. this Journal, 1895, p. 339. 
t Flora, lxxxviii. (1899) pp. 86-99 (16 figs.). Cf. this Journal, 1897, p. 418. 
