1897] POLYMORPHISM IN THE ALGAE 109 
stances as a Dactylococcus, and the latter as a Scenedesmus. 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 toa 
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 Plewrococcus vulgaris can grow out into a Stigeocloniwm, 
it must be assigned to the branched filamentous type of algae. But 
Chodat says, “I do not think that Plewrococcus 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 
Plewrococcus is to be considered a degeneration-form of a Stigeo- 
clonium, 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 Raphidiwm polymorphum (or 
braunit), one obtains a picture of a species which for excentricity 
certainly leaves nothing to be desired, and which is unique in the 
organic world. Raphidiwm, according to Borzi, belongs to the 
cycle of forms of various higher algae (Prasiola, Ulothriz, ete.) ; 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 Raphidium 
(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 Plewrococcus, Raphidiwm, ete. 
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 
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