484 SUMMABY OF CURRENT RESEARCHES RELATING TO 



advancing to the truly septated forms, such as the Mesocarpeae and 

 Zygogonium which are truly isogamous, and finally, through Zygnema 

 and Spirogyra, in which heterogamy is indicated by the immobility 

 of one of the reproductive bodies, to Spirogonium with morphological 

 differentiation of the sexual organs. 



The lowest member of the filamentous Confervacese is the TJlotri- 

 chaceae, starting at once from the Sciadiese, and still displaying 

 isogamy. From the Ulotrichacese spring the branches with a varying 

 degree of differentiation, viz. — (1) The Cladophoreae and ChaBto- 

 phorese, isogamous, with a filamentous thallus ; (2) the Ulvacese, iso- 

 gamous, with a membranous thallus ; (3) the Mycoidese, parasitic 

 and heterogamous, with oospheres and poUinodia ; (4) the Sphaero- 

 pleeae, which give origin directly to the CEdogoniese, and these again 

 to two branches, the ColeochgeteEe, CharaceaB, and Muscineae. Possibly 

 a fifth branch, unknown in its early stages, gives birth to the Florideae. 



The blue-green algae attain but a very limited development, the 

 principal branches being the Oscillarieae, filamentous and reproduced 

 only by cysts, the Merismopedieae with a membranous, and the 

 Chroococcaceae with a massive thallus, the Nostocaceae, characterized 

 by the production of heterocysts, the Eivularieae, and the Scyto- 

 nemeae. 



The brown algae commence with the Diatomaceae, which are con- 

 nected with the higher forms through Hydrurus and Chromophyton, the 

 latter, with mobile zoospores, establishing a passage to the Phaeo- 

 sporeae. At the base of the Phaeosporeae are the Ectocarpaceae, re- 

 produced by non-sexual zoospores and by undifferentiated gametes, 

 advancing then to the Sphacelarieae, Laminarieae, and Punctarieae. 

 Starting from these lower forms are three distinct more highly differ- 

 entiated branches, the Dictyoteae, Cutleriaceae, and Fucaceae, the last 

 representing the highest type in the complete suppression of non- 

 sexual reproduction. 



The evolution of the Florideae is traced by the authors from its 

 youngest group the Bangiaceae, which are closely allied to the Con- 

 fervaceae and XJlvaceae, through the Nemalieae (Batrachospermeae and 

 Helminthocladeae), whence are developed two parallel series of 

 families. In the first of these, consisting of Gelidieae, Cryptonemieae 

 and Squamarieae, the oosphere developes directly into a sporogonium ; 

 in the second series, which includes the Ceramiaceae, Ehodomeleae, 

 Ehodymeniaceae, and Corallinaceae, it is not the oosphere, but an 

 auxiliary cell in its neighbourhood, which, after receiving the 

 contents of the latter, divides, like the oosphere itself in the first 

 series, and gives birth to the sporogonium. 



Agardh's Floridese.* — The most recent volume of Prof. J. G, 

 Agardh's ' Contributions to the Systematic Classification of Algae ' 

 is devoted to the Floride^, and contains descriptions of three new 

 genera and between fifty and sixty new species. The new genera 

 are : — Titanophora, belonging to the Nemastomeae, with two species, 



♦ Agardb, J. G., ' Till Algernes Sybtematik,' VII., Floridese, 117 pp. aud 1 pi., 

 4to, Lund, 1886. See Nature, xxxiii. (1886) p. 458. 



