Archer — On a Minute Nostic with Spores. 315 
enter into the ' gonidia question.' " The fact that these latter form 
independent "spore-cells" (reproducing the plant), he would seem, so 
far as we can judge, to hold as having no material, if any, bearing on 
the question, for he dwells only on their being submerged as giving 
them an immunity. " But in any case," he says, afterwards, further 
on, as regards the question, "whether certain species of Cylindro- 
spermum pass into the ' gonidia state' [that is, become the basis of 
Collemaceae] remains for so long doubtful, till the transition, here alone 
decisive, be observed. In the Collema-thallus itself a decision is of 
course no longer possible, since the spores characteristic of Cylindro- 
spermum apparently just as little come to development in the gonidial 
state, as do the 'manubria' of the Rivulariese." (This last allusion 
has a bearing on Lichina, &c., which the author thinks have plants 
appertaining to Eivulariese for their basis, but without manuhria.) I 
would venture to suggest, were such Algge as these truly seized upon 
by this completely innocuous parasite — nay, which, if the hypothesis 
be true, rather tends to favour the growth and vigour of the "gonidia" 
— we should hardly expect that, on the other hand, the innate or inhe- 
rited tendency to produce "spores" would at the same time become 
wholly extinguished. It would, I should venture to suppose, seem 
probable, even admitting the views of Schwendener and Reess as re- 
gards Nostoc, that Cylindrospermum is not likely to have anything to 
say to the "gonidia question." But the isolated observation, for the 
first time herein recorded, would seem to show that iN'ostoc, too, may 
form spores, though it be, indeed, so very exceptionally, and so 
extremely rarely. 
The main object, then, of the present communication is to offer the 
following three suggestions which occur to me : — 
1. To suggest the possibility that, if we may conceive Dolichosper- 
mum, &c,, excluded from the " gonidia question " as forming special 
fruit (that is, "spores"), so might we regard Nostoc as excluded, 
though its formation ofsporesbeso extremely rare. Seemingly, indeed, 
the capacity of forming spores by an algal species, supposed to become 
occasionally lichenized, is not a reason against the hypothesis as viewed 
by Schwendener — he only assumes that such an example of the alga 
surrenders, or leaves in abeyance, its tendency to the production of 
spores. 
2. To suggest that there are veritable lichens which live submerged, 
and produce their apothecia. I presume, however, it might be replied 
that such may have received their inoculation by the parasite during 
some season of drought, when the alga lay "high and dry." 
3. To suggest the possibility that the spores of Collema, if "sown" 
on some other gelatinous substratum, besides that of JSTostoc — say, for 
instance, a Palmella or Mesotsenium — might equally well germinate, 
penetrate therein, and develop a hypha. 
There seems, I venture to think, no d priori reason against this 
latter supposition — inside the Kostoc, the "reserve-stuff" of the spore 
being exhausted, and the chains of Nostoc fihiments admittedly intact, 
