Akchkr — On a Minute Nostic with Spores, 313 
upon the substance of JS'ostoo, and a description of the experiment and 
its results forms the subject of his memoir previously alluded to."^' He 
states, indeed, that the spores of Collema can be readily enough made 
to germinate upon any moist substratum, such as a glass -plate, stones, 
and so on, and will slowly produce even a branched and sparingly 
jointed growth, but this goes on only so long as the reserve-stuff is sup- 
plied by the spore, but when this is exhausted the hj^pha-mass thus 
produced, though it may survive even weeks, will then slowly die off. 
But when he brings a spore or the young hypha upon the ]S"ostoc, it at 
once becomes further developed, sending more or less copiously through 
its surface many branches, and penetrating within. Soon, however, 
they cease to increase in length, become swollen at the points and at 
other places, and become attached by these swellings upon the Nostoc. 
Thereupon thinner processes become sent further into the gelatinous 
mass of the Nostoc, from the swellings ; these become branched, and, 
tortuously surrounding the chains of gonidia, form, in fact, the '^Col- 
lema-mycelium," and the complete transformation or conversion of the 
*']S'ostoc" into the Collema is brought about by the hypha producing a 
peripheral stratum of fibres, from which break forth, through the 
i^'ostoc-jelly," the first root-hairs. Such an artificially produced 
" Collema" the author had not been able to rear up as far as the pro- 
duction of fructification (apothecia), but he doubts not the tenability of 
the assumption that every Collema in free nature is a Nostoc,^^ thus 
made the nidus for the development of the spores, evolved of course 
from a preceding "JNTostoc" so naturally inoculated (as one might say), 
that is to say, in other words, a preceding compound organization which 
is known as *' Collema." Such is, as briefly as possible, the result of 
Reess's experiences, and the views he holds ; it would lead too 
far to endeavour to go more closely into the arguments and state- 
ments of Eeess and Schwendener — those of the latter applied to 
the Lichens at large, not the CoUemaceae only — but it may not be 
wholly without use to have directed attention to their remarkable 
memoirs. 
Basing his opinion, as it would seem, at least mainly, upon the 
result of the experiments of Professor B-eess alluded to, Professor Cohnf 
would exclude the CoUemaceae from the Lichens, which (without 
these), as a Class, he would retain, remarking that ''he knows no Algce 
which could be transformed by the influence of a fungus into Usnea, 
Cladonia, Cetraria, etc., but that it appears to him that the parasitism 
has been rendered by de Bary and Reess extremely probable for the 
* CoUemaceae.' '* 
Schwendener himself, in his later memoir, J figures certain IS'ostoc 
* Prof. Reess — " Ueber die Entstehung der Flechte Collema glaucescens, Hoffni. 
durcli Aussaat der Sporen derselben s^niNostocluhenoides^l'QxiQh.y in "Monatsb. 
der k. Akad. der Wissensch. zu Berlin," Oct. 1871, p. 523. 
t Prof. Dr. F. Cohn — "Conspectus Familiarnm crytogamarum secundum me- 
thodnm naturalem dispositarum," in " Hedwigia," No. 2, 1872, p. 17. 
+ "Die Algentypen," etc., pp. 28, 99, t, II., ff. 13-15. 
R. I. A. TROC. — VOL. I., SER. 11., SCIENCE. 2 S 
