314 
Proceedings of the Boyal Irish Acadenii/. 
specimens whose gelatinous matrix is seen to be penetrated by what he 
denominates fungal threads (Pilsfaser), and these he points to as evi- 
dence of the truth of his view ; that is, that they become the hypha, 
and that the phenomena of growth thereby induced absolutely convert 
the '^Nostoc" into " Collema;" and he firmly holds his figures proz;^ 
the case. IS'ow, Eeess, referring to these very figures, conceives the 
fungal threads depicted must be strictly those of a (destructive) fungus 
— a mould, in point of fact ; he thinks, indeed, they may be anything 
whatever, iDut one thing clearly he avers, be they what they may, they 
are by no means a Collema-hypha, founding his opinion, of course, 
upon the knowledge gained from his recently conducted experiments. 
So that whatever may be the opinion of other observers as to the result 
of the researches of Reess, at least the examples adduced by Schwen- 
dener relating to Collema, it would appear, must be held as incon- 
clusive. 
It may, perhaps, be not inopportune to observe that, as must be 
well known, the gelatinous masses of those Algae which grow on wet 
rocks and such situations, be they Palmellaceous or Chroococcaceous, 
are prone to be more or less permeated by ''myceloid" threads, and 
even some such as would fairly well accord with those Eeess depicts 
for Collema, though not so copiously branched, may not be unusual. 
Some of these threads are, at least occasionally, those of indubitable 
(devastating) fungi, which, when they ''attack" certain cells, destroy 
them ; other threads, doubtless quite distinct, can apparently live inde- 
pendently and innocuously, though probably drawing nutriment from 
the common mucous matrix. "What a monstrous and abnormal "Lichen- 
thallus" thus not unfrequently comes to view — a variable "hypha" 
interruptedly running hither and thither, and accompanied by "goni- 
dia of very heterogeneous character ! The plant named by Kiitzing, 
Trichodictyon rupestre^ which can hardly be doubted to be the same as 
Cylindroci/stis crassa^ de Bary, is frequently (though not always) 
accompanied by a number of fine filaments (which seem, however, to 
be inarticulate), twisted in and out through the gelatinous mass made 
by the alga, but so running as to leave rounded spaces between, con- 
taining the groups of the Cylindrocystis-cells ; they seem, in fact, to 
urge their way between the more dense mucous envelopes formed round 
the groups of dividing cells, simply because they find the intervals, 
being softer, more readily permeable. These filaments, whatever 
their nature really may be, cannot be doubted, I should think, to be 
foreign, though they were introduced into the generic characters by 
Kiitzing, being considered by him as somehow a portion of the struc- 
ture of the alga, which, indeed, itself reproduces by conjugation, and 
is, no doubt, in fact, a desmid. 
Schwendener claims as the foundation or basis for the production of 
" Collemacese" only such nostochaceous plants as live in moist or wet 
habitats — the entirely aquatic forms (Trichormus, Sphaerozyga, Cylin- 
drospermum, Dolichospermum), he considers, being inaccessible under 
water, are protected from the attack of the parasite, and thus ''cannot 
