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gonidia were produced from the intermediate joints of the 
hypha and not from the terminal cells. If, then, the figures 
by which he illustrated his original views upon this point were 
correct, as they presumably were, it is a legitimate inference 
that the change in his opinion more immediately originated in 
the desire to obtain additional confirmation of the fundamental 
principle of his theory already noticed by pressing the connec- 
tion, real or assumed, of the hypha to the “ alga ” (gonidia) 
into his service. It is, indeed, very difficult, as every lichenist 
who has made the experiment well knows, to trace this connec- 
tion except in the earliest stages of lichen development, and 
even there only under exceptionally favourable circumstances. 
Hence the various experiments already noticed in lichen- 
culture were instituted chiefly for the purpose of ascertaining 
a primo initio what was the origin and the character of this 
relationship. And here we may observe that from those 
recorded, which are in various respects confessedly unsatisfac- 
tory and inconclusive, the hypothesis in reality derives little or 
no support, since in great part, at least, the phenomena 
witnessed, or said to have been witnessed, are capable of 
another and more probable interpretation. Thus, with respect 
to Keess’ famous experiment with Nostoc and Collema spores, 
there can be little doubt that Nylander’s hypothesis, as ex- 
pressed in “Flora,” 1868, p. 353, et alibi , is correct, viz. that 
“Nostoc” is in part, if not altogether, a rudimentary or un- 
developed state of “Collema,” analogous, as it were, to the 
“leprarise” amongst the Lichenacei. He has observed that 
nostocine thalli are frequently met with in sandy and gravelly 
places, and in the same spots shortly afterwards are found 
Collema pulposum, which entirely agrees with our own obser- 
vations on chalky detritus at Shiere in Surrey, and in the case 
of various other species of Collemacei on gravelly soil in the 
West Highlands. This certainly seems a much more natural 
solution than the “ dimorphic ” theory of Dr. Muller in “ Flora,” 
1872, p. 90. But even were this not the relation between 
Nostoc and Collema, the experiments of Beess would, after all, 
prove absolutely nothing in favour of his theory in this particu- 
lar instance ; for had he sown the spores of a Parmelia or 
Opegrapha upon the nostoc, he would have witnessed a similar 
phenomenon. So, also, with respect to the filament germs 
seen by Bornet and Treub entering into Protococcus . This, 
again, would not prove the position taken up by them, for 
M. Norman, an equally practical and distinguished observer, 
has seen hyphse surrounding the chlorophyll of Jungermannia 
and its grains of pollen, vid. “ Allelositismus,” 1872, pp. 249 
and 252. But though from the nature of the case thus 
difficult to be correctly ascertained, and though the results of 
