ON LICHUENOUS FRUCTIFICATION ON ALG. 3 
that the spores of this self-same Lichenospheria Lenormandi 
should afterwards grow upon and into another species of 
Strosiphon, or say even into a Scytonema, then some of the 
*‘ specific characters’ as given, nay, even probably some of 
the ‘‘ generic,” would disappear and others take their place. 
It is to be granted, indeed, that on the new theory, when a 
Nostoc becomes invaded by the parasite which converts it 
into a Collema, a very considerable alteration is produced on 
even the outward aspect of the Nostoc ; instead of a rounded, 
lobed, “blobby,” and soft lump, it becomes more or less 
foliaceous, less watery, and more subdivided, but it is the 
alga all the time which submits to this alteration, the true 
lichen is inside, only evincing itself externally by its apothecia 
and by its action on the alga (like a gall causing even greater 
modifications on a hizher plant) inciting those changes of 
external aspect, whilst the alga is at the same time making 
use of its assimilating power to do for the lichen what it 
cannot do itself. 
There can be little doubt but that amongst these Scyto- 
nematous and Sirosiphonaceous alge quite distinct forms 
occur; but, on the other hand, there can be almost as little 
doubt but that Kuitzing has vastly over-enumerated them, that 
many of his so-called species are not distinguishable. Now, 
it is hard to conceive that one and the same parasite would 
care very much which of forms so closely resembling it 
invaded in order to pursue its course of life. Sirosiphon 
divaricatus seems not to differ much from S. alpinus ; it is 
more fructiculose, the cells in the central stems seem to occur 
in greater than double series ; what very perceptible barrier 
is there to the supposition that the parasite, which invades the 
former to form Lichenospheria Lenormandi, Bornet, might 
not at another time invade the latter? Would it not then 
fructify in the same way, show spores alike, &c.? But the 
parasite which does really invade the latter is not the same 
as the figure herewith will show, not to speak of the para- 
physes, so prominent a feature in the latter being absent in 
Bornet’s plant. Are these Scytonemicolous and Sirosiphoni- 
colous parasites, then, so extremely particular in their choice ? 
See again the two Scytonemata, resembling in themselves 
so much and yet with ‘ parasites” so distinct; the spores 
could not be confounded for a moment (see figs. 1, 2, and 
fig. 8). Again, see the great resemblance (but certainly not 
identity) between the spores in the second Scytonema and in 
Sirosiphon pulvinatus, alge mutually sufficiently unlike (see 
figs. 8 and 28). 
It might again be asked whilst the new theory is, as it 
