On the Polymorphism of the Green Algae and 
the Principles of their Evolution '. 
BY 
Dr. ROBERT CHODAT, 
Professor of Botany in the University of Geneva. 
HE classification of the Chlorophyceae has from time to 
JL time been the subject of numerous discussions, and even 
now it is by no means considered as settled. After comparing 
the different systems proposed by Rabenhorst 1 2 , Gay 3 , Klebs 4 , 
De Toni 5 and others, it is easy to understand how it could be 
possible for so distinguished a botanist as Sachs 6 to say : ‘ It 
is certainly a great mistake to oppose the Chlorophyceae to 
the other Algae (Cyanophyceae Rhodophyceae,Phaeophyceae) 
as a distinct type ; such a division has nearly the same value 
as one in which the Phanerogams destitute of chlorophyll 
should be opposed to the green Phanerogams and in which 
both should be considered as distinct types. In the Chloro- 
phyceae of the systematist several archetypes lie hidden, each 
of which corresponds in its phylogenetic rank to the Arche- 
goniatae, the Florideae, the Phaeophyceae, &c. It is not 
possible, however, in the present stage of investigation of the 
1 Read before the Botanical Section of the British Association at the Liverpool 
Meeting, 1896. 
2 Rabenhorst, FI. Europ. Algar. 
3 Recherches sur le developpement et la classification des Algues vertes, Paris, 
1891. 
4 Ueber die Organisation einiger Flagellatengruppen, Untersuch. aus dem Bot. 
Institut, Tiibingen, 1881-5, p. 300, and Beitr. z. Kenntniss niederer Algenformen, 
Bot. Zeit. 1881. 
5 Sylloge Algarum. 
6 See Sachs, Phylogenetische Aphorismen, Flora, 1896, p. 199. 
[Annals of Botany, Vol. XI. No. XLI. March, 1897.] 
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