998 REPORT—1896. 
By giving things different names we do not prove that the things themselves are 
different. In this case, for example, the multiplication of terms serves, in my 
opinion, merely to diseuise the facts. The reproductive cells produced by the 
ordinary plant of an CEdogonium are identical in development, structure, behaviour, 
and germination with those produced by the odspore. The term ‘zoogonidia’ applied 
to the former is a ‘question-begging epithet,’ for it assumes that they are not 
homologous with the ‘ zoospores 4 produced by the latter. I prefer to keep the old 
name zoospore for both, as they are identical bodies. 
To my mind the point seems to be this. An Cdogonium (to keep to this 
example) can form zoospores at any stage of its development ; there is one particu- 
lar stage, however, at which they are always formed—namely, on the germination 
of the odspore. Nothing new is intercalated, but the irregular and indefinite 
succession of sexual and asexual acts of reproduction is here tending to become 
regular and definite. rt 
In Spheroplea, as was well pointed out by the late Mr. Vaizey,' though his 
view of alternation was very different from that which I am now putting forward, 
the alternation is as definite as in a moss, for here, so far as we know, zoospores 
are only formed on the germination of the fertilised ovum. If Spheroplea stood 
alone we might believe in the intercalation of these zoospores, as a new stage, but 
the comparison with Ulothrix, Gidogonium, Bulbochete and Coleochete shows, I 
think, where they came from. : 
The body formed from the odspore is called by Pringsheim the first neutral 
generation. In Gidogonium this has no vegetative development, for the first thing 
that the odspore does is to form the asexual zoospores, and it is completely used up 
in the process. In other cases it is not in quite such a hurry, and here the first 
neutral generation has time to show itself as an actual plant. This is soin Ulothrix, 
a much more primitive form than Gdogonium, for its sexuality is not yet com- 
pletely fixed. Here the zygospore actually germinates, forming a dwarf plant, and 
in this stage passes through the dull season, producing zoospores when the weather 
becomes more favourable. On Pringsheim’s view the dwarf plant is not a new 
creation, but just a rudimentary Ulothrix, which soon passes on to spore-formation. 
So, too, with the cellular body formed on the germination of the odspore 
of Coleochete; this also is looked upon as a reduced form of thallus, On any 
view this genus is especially interesting, for the sporophyte remains enclosed by 
the tissue of the sexual generation, thus offering a striking analogy with the 
Bryophyta. 
In the Phycomycetous Fungi—plants which have lost their chlorophyll, but 
which otherwise in many cases scarcely differ from Algze—the odspore in one and 
the same species may either form a normal mycelium, or a rudimentary mycelium 
bearing a sporangium, or may itself turn at once into a sporangium (producing 
zoospores) without any vegetative development. Here it seems certain that 
Pringsheim’s view is the right one, for all stages in the reduction of the first neutral 
generation lie before our eyes. Nowhere, either here or among the green Algiv, 
do I see any evidence for the intercalation of a new generation or a new form of 
spore on the germination of the fertilised ovum. 
Pringsheim extends the same view to the higher plants. The sporogonium 
of a moss is for him the highly modified first neutral generation, homologous with 
the vegetative plant, but here specially adapted for spore-formation. I have 
elsewhere pointed out* that this view has great advantages, for not only does it 
harmonise exactly with the actual facts observed in the green Algze and their allies, 
but it also helps us to understand the astoundingly different forms which the 
archegoniate sporophyte may assume. 
Tt seems to me that Pringsheim was right in regarding the fruit-formation of 
Floride as totally different from the sporophyte-formation of Coleochete or the 
Bryophyta. The cystocarp bears none of the marks ofa distinct generation, for 
throughout its whole development it remains in the most complete organic connec- 
1 Annals of Botany, vol. iv., p. 373. 
2 Nature, February 21, 1895. 
