1897] POLYMORPHISM IN THE ALGAE 109 



stances as a Dactylococcws, and the latter as a Sccnedesmus. But in 

 spite of all his belief in the existence of transitions between the 

 various forms of lower algae, in spite of the fluctuation of all their 

 characters and of the melting away of all limits, Chodat still holds to a 

 certain independence in the various types ; only it does not appear from 

 anything he says whether the deviations from these types are due to 

 the definite effects of external conditions or whether they belong to 

 constant varieties or races. Neither has Chodat always drawn 

 accurate inferences. If his observation is correct, that the already- 

 mentioned Pleurococcus vulgaris can grow out into a Stigeoclonium, 

 it must be assigned to the branched filamentous type of algae. But 

 Chodat says, " I do not think that Pleurococcus is a state of a higher 

 alga. I think that it must be considered as a type degenerated 

 through the influence of its habitat, and which in water and under 

 favourable conditions can tend towards its primitive state." Thus 

 Pleurococcus is to be considered a degeneration-form of a Stigeo- 

 chmiam, although it behaves as an independent simple alga. If one 

 takes the observations of Chodat and Borzi together, so far as they 

 relate to the same form, for instance Baphidium polymorphum (or 

 braunii), one obtains a picture of a species which for excentricity 

 certainly leaves nothing to be desired, and which is unique in the 

 organic world. Baphidium, according to Borzi, belongs to the 

 cycle of forms of various higher algae (Prasiola, Ulothrix, etc.) ; it 

 is produced in this way — two zoospores, in consequence of their 

 escape from the sporangium taking place abnormally, grow together 

 by their hinder ends, and this pair then turns into a Baphidium 

 (Borzi, 1895, p. 231, " My cultures exclude all doubt as to this 

 fact "). If it had not been such a well-known and eminent algologist 

 as Borzi who put forward these opinions they would not have been 

 worth the trouble of wasting a word upon, but under the circum- 

 stances they must be taken into account. In any case it is clear 

 from what has been said, that unlimited confusion prevails in the 

 classification of the lower algae, and that the most contradictory 

 views are held even about the simplest and commonest organisms 

 such as Pleurococcus, Baphidium, etc. 



We cannot decide on theoretical grounds whether a form is 

 independent or genetically connected with another. It has in fact 

 happened in the history of the subjects that forms which at one 

 time were considered independent have been certainly proved to be 

 developmental states of other species. It is conceivable that out of 

 the enormous number of described species of algae many others will 

 meet with the same fate. The only possible way to arrive at clearness 

 and knowledge is to use a -scientific method which will stand the 

 test of criticism. 



It is remarkable that so little has been learnt from the history 



