Notes. 
375 
The Siphoneae have also been excluded, for although there is in 
some of them a sort of alternation of generations, it has plainly 
originated within that group, and differs in essential points from the 
alternation of generations in the Confervoideae, Mosses, Ferns and 
Flowering-plants. This alternation is seen typically in Acetabularia , 
but I may point out that the so-called spores of Acetabularia are not 
really spores at all, but gametangia, which separate from the vegetative 
body before the development of the gametes ; they are reproductive 
organs, not reproductive cells. In the formation of the resting-spores 
whose contents break up into a number of swarm-spores (gonidia) or 
amoeboid reproductive cells in Botrydium and Vaucheria , there is an 
analogy with the development of the gametangia of Acetabularia , the 
resting cells being sporangia. 
The Rhodophyceae and Characeae I have reserved for special 
treatment. 
In the Rhodophyceae or Florideae there is an undoubted alternation 
of generations of the same nature as that in Coleochaete ; and, except 
that in the more specialized forms the distinct individuality of the 
female reproductive cell is either lost or, through the extreme com- 
plexity of the female reproductive organ, is all but impossible to trace, 
and also that there is the red colouring matter in the cells, the 
Florideae might almost be classed with Coleochaete and its allies, for 
the more rudimentary forms like Nemalion and Batrachospermum have 
a female organ (procarp) differing very little if at all from the 
oogonium of Coleochaete. 
In the life-history of Chara there certainly seems to be an alterna- 
tion of generations, but taking place in a way different to what Vines 1 
supposed, I believe. According to Vines’ view the sporophore was 
represented by the proembryo which was supposed to have become 
aposporous and to produce the oophore by lateral budding, a method 
of development quite unknown in any other Alga. The chief objection 
to this view seems to me to lie in that it gives no explanation of 
certain facts in the early development of the proembryo. I may 
remind you that when the oospore of Chara germinates it divides into 
three cells by two divisions ; the first division plate is formed parallel 
to the equatorial plane, dividing the oospore into two unequal parts ; 
the smaller is then divided by a wall at right-angles to the first. 
1 Vines, Journ. Bot. 1878 : see also Annals of Botany, vol. i. p. 177. 
