PAPENFUSS: CLASSIFICATION OF THE ALGAE 167 



Clarke (1951a) with respect to Pylaiella and Laminaria. It is of interest to note that in 

 the sperms of Fucus it is also the anterior flagellum that is of the tinsel type (Manton 

 and Clarke, 1951b). 



History: For some fifty years after the publication of Linnaeus' Species 

 pluntarum (1753) almost all nonmembranous parenchymatous or pseudoparen- 

 chjTiiatous algae (brown, red, and green forms such as Caulerpa) were referred 

 to the genus Fucus. (For the long pre-Linncan history of this genus the reader 

 is referred to tlie interesting article by Church, 1919a.) Stackhouse in his Ne- 

 reis hritannica (1795-1801) and later in his Tentamen marino-cryptogamicimi 

 (1809) was the first to recognize the heterogeneity of this genus which he ac- 

 cordingly subdivided into a large number of genera, a few of which {Chorda, 

 AscophyUum, Bifurcaria) arc still accepted as genera of brown algae. 



Largely on the basis of their brown color, Lamouroux (1813) erected a group 

 ("ordre"), Fucacees, for some of the genera of this phylum. He, however, ex- 

 cluded from the Fucacees the members of the Dictyotaceae, which he regarded 

 as representative of a separate ''ordre," Dictyotees. 



C. Agardli (1817) changed Lamouroux' designation to Fucoideae and consid- 

 ered these algae as constituting one of the five sections into which he divided 

 the algae. Like Lamouroux, C. Agardh failed to make a sharp separation of the 

 algae on the basis of color. In 1817, he placed the Dictyotees of Lamouroux in 

 his section Ulvoideae. In 1824 he removed them to the Fucoideae but he still 

 kept the filamentous brown algae in the Confervoideae. 



With few exceptions, the autonomy of the brown algae was henceforth ac- 

 cepted as an established fact. On account of their brown pigment, Harvey 

 (1836) named them Melanospermeae, which designation was changed to ]\Iel- 

 anophyceae by Ruprecht (1851). Thuret (1850) created the name Phaeosporeae 

 for one of the major taxa into which he (1855) divided the group. De Bary 

 (1881) coined the designation Phaeophyceae, which is now generally accepted 

 as the class name of the group. 



The discoveries relating to sexuality and of alternation of generations in the 

 Phaeophyceae contributed immensely to an understanding of the life histories 

 of thallophytes. The two kinds of reproductive organs characteristic of a large 

 majority of these algae were named oosporangia and trichosporangia by Thuret 

 in 1850 (pp. 235, 236), but shortly afterwards (1855, p. 15) he proposed the 

 subsequently employed terms unilocular and plurilocular sporangia. Thuret 

 found that the swarmers from the two kinds of sporangia were morphologically 

 similar, except for size, and remarked (1850, p. 236), "J'ai vu d'ailleurs germer 

 les uns et les autres, ce qui prouve suf!isamment leur complete identite." 



Studying Fucus, Thuret in 1853 observed for the first time in brown algae 

 that only eggs to which sperms had had access would germinate. His classical 

 illustrations of the reproductive organs were published in 1854. Strasburger in 

 1897 saw the fusion of the egg and sperm nuclei and established that the plants 

 are diploid. His cytological observations were confirmed by Farmer and Wil- 

 liams (1896, 1898) and by Yamanouchi (1909a), who also esta])lished that meio- 

 sis occurs during the first two divisions of the primary nucleus of the oogonium 

 and antheridium. Fucus (and this is true of related genera also) thus was shown 

 to have a life history analogous to that of animals. 



The next brown alga in which a conjugation of gametes was observed is 



