1 20 Chodat. — On the Polymorphism of the Green 
two motile hetero-gametes and the true sexuality realized 
in the higher types. The form of the oogonium of Coleochaete 
is simply a fortuitous resemblance to the archegonium, and is 
not sufficient to establish any homology. 
The analogy with Oedogonium , in which the two gametes 
may be compared to two differentiated zoospores, is much 
more marked. The number of antherozoids arising from one 
cell is also comparable, and their origin is quite different from 
that of the antherozoids of Mosses and Ferns. 
All this very clearly indicates a direct affinity between 
the Coleochaeteae and the Green Algae, which considered 
as a whole group (the Siphoneae put aside) is quite as natural 
a one as the Archegoniatae. 
With regard to the so-called sporogonium of Coleochaete , 
there is no dispute about the statement that the ovum 
undergoes division after fertilization ; but this segmentation, 
which reminds one to a certain degree of the production 
of the sporogonium in some lower Liverworts, shows a far 
greater resemblance to similar products in the Green Algae. 
The fertilized zygote of Hydrodictyon divides during 
germination into several zoospores ; the same thing is known 
to occur in Oedogonium. In some Volvocineae, such as 
Gonium , according to my observations, the zygote gives birth 
to four zoospores with gelatinous envelopes, whilst in others 
the zoospores are extruded before division. 
From the fact that in the case of Coleochaete the ovum 
is more protected by the formation of a resistent envelope, 
germination becomes slower ; and as I have already shown 
that the transformation of zoospores into spores and finally 
into autospores may be effected, it is evident that a similar 
adaptation takes place here. 
The little thallus of Coleochaete cannot be contrasted with 
the antecedent plant as an entirely new formation ; according 
to all analogies with other Algae, it constitutes simply the 
beginning of a normal plant, only modified under peculiar 
circumstances. Similar small thalli are moreover formed in 
Aphanochaete , but from zoospores. This is merely the result 
