356 Bower . — On antithetic as distinct from 
different ways, or by fragmentation of the protoplasmic con- 
tents, these rounding off and forming cell-walls round each of 
the portions. In the formation of the swarm-spores the 
processes are essentially similar in nature, though different in 
detail, from those in Vaucheria , while in the various forms of 
resting spores, and even in those spores from which the 
gametes are derived, I think we see developments more or 
less closely comparable to the Gongrosira stage of Vaucheria. 
They may all be placed in the category of adaptations of the 
gametophyte itself to external circumstances, and at best we 
have here only an alternation of adaptive stages resulting 
from the differentiation of generations, homologous with one 
another — all being potential gametophytes. But Rostafinski 
and Woronin took a different view 1 : they styled the vege- 
tative plant a ‘ sporophore generation/ while the ‘ oophore ’ 
is represented by the sexual gametes which form the zygote, 
this being itself the limit of the two generations 2 . Comparing 
Botrydium with other Chlorosporeae they say that ‘ Botry- 
dium affords us an alternation of generations in which the 
existence of the vegetative plant falls in the post-embryonal 
period of life, as in the Ferns. In all other Chlorosporeae it 
is otherwise, as in the Moss ; the vegetative plant arises from 
the spore, not from the ovum.’ Hence we are to conclude 
that within the natural family of the Siphoneae the Vaucheria 
plant is the gametophyte, and the Botrydium plant the sporo- 
phyte, the comparison being strengthened by allusions to the 
Ferns and Mosses! I have chosen this example because it 
brings out very clearly the fundamental fallacy which under- 
lies such a comparison : the term spore is by these authors 
applied to certain round bodies produced within the Botrydium 
plant under certain circumstances : it is assumed that, because 
they are round, limited by a cell-wall, and that from them 
the gametes are derived, therefore they are comparable to the 
spores of the Mosses or Ferns. But why should there be 
anything in the life-history of Botrydium strictly comparable 
to the spore of the Moss or Fern ? It is exactly this assump- 
1 1. c., p. 666. 2 1. c., p. 663. 
