A Igae and the Principles of their Evolution. 1 1 9 
plant, which likewise bear four cilia and are smaller. The 
male gametes are formed in the same way, rarely two in one 
cell, but the gelified vesicle is rapidly dissolved and fecundation 
can be effected. The fusion of the male gamete with the 
very sluggish oosphere, which is at this moment always in 
front of the empty oogonium, has been observed. It may 
be compared with the corresponding process in Coleochaete ; 
in the two genera the oogonium and zoospores are homo- 
logous. The oosphere and antherozoid have the same shape 
and the same number of cilia as the zoospores. In Coleochaete 
pulvinata *, for example, the oogonia and the cells which give 
birth to the zoospores are terminal cells. The antheridia 
in both genera are also of the same morphological rank ; 
each antherozoid can be compared to a micro-zoospore. To 
this it may be added that the cells of Coleochaete are provided 
with chromatophores of the same shape, containing the same 
pyrenoids ; and the hairs and zoospores are so clearly allied 
to those of the Chaetophoraceae and other Green Algae that 
we may justly feel greatly surprised to read in a serious paper 
that the Coleochaeteae 2 ought to be united with the Arche- 
goniatae, and separated from the Chlorophyceae. It is true 
the author admits that there is no direct passage from the 
Coleochaetae to the Mosses and Ferns. On the other hand, 
this direct relationship does actually exist betw r een this group 
and the other Chaetophoraceae. Aphanochaete is beyond all 
doubt the connecting link which unites the two nearly allied 
groups ; in fact, the only difference between the two consists 
in the fact that in Coleochaete the oosphere is not motile, and 
remains enclosed in a sort of archegonium. But it must be 
remembered that in the other genus the oosphere is almost 
motionless and remains in front of the oogonium. 
If, as we are permitted to believe on comparison with 
similar cases, the oosphere is merely a macro-gamete which 
remains enclosed in the cell- wall, the stage of Aphanochaete 
is of the greatest interest, being the intermediate step between 
1 Pringsheim, Jahrb. fiir wiss. Bot., Band II. 
2 Sachs, loc. cit., pp. 184, 185, &c. 
