22 THE AMERICAN MONTHLY [February, 
supposed to be related, we must not lose sight of the fact that there are un- 
doubted resemblances, and that the points of resemblance are of just that kind 
which is held by naturalists to indicate close relationship. 
If we exclude entirely the gonidia, there is then no reason why all lichens 
should not be distributed among the following fungal orders, viz: Pyreno- 
mycetes, Discomycetes,and Hymenomycetes. Not only are the resemblances 
sufficient for including the various forms under the orders given, but scarcely 
a new family would need to be made, and in many cases the lichens would 
go without difficulty into fungal genera already established. We do not 
believe that such a classification of the lichens among the fungi would be a 
convenient arrangement for purposes of lichenological study, but the facts are 
as stated. 
With gonidia the resemblances to free alge are even stronger. So far as 
structural characters go, the following families of alge are surely represented 
among lichen gonidia: Chrodcoccacee, Nostocacee, Strosiphonee, Scyto- 
nemocee, Rivulariacee, Palmellacee, Confervacee, Chrodlepidee, and 
Coleochetee. ‘There are scarcely any forms of gonidia that cannot be referred 
to established algal genera, and many exhibit no specific differences from 
well-known forms of alge. 
It has been suggested by some autonomists that these resemblances between ~ 
gonidia and free alge may be explained on their theory by supposing that 
all the gonidia-like alge are in fact gonidia, which were originally produced 
by lichens, but which now lead an independent existence and multiply. 
Famintzin and Baranetsky were led to this conclusion by their researches on 
the behavior of lichen-gonidia when they are set free by the decomposition 
of the hyphal tissue in water. They found that the gonidia lived in every 
way like the alge they resembled ; all differences of form disappeared, and 
they multiplied not only by fission, but in some cases zo6spores were pro- 
duced. ‘These observations, while they greatly strengthen the view that there 
are no differences between gonidia on the one hand and certain alge on the 
other, except such disagreement as can be accounted for by their dissimilar 
conditions of life, still give us not the slightest proof that gonidia are ever de- 
veloped from hyphe. If this explanation of the autonomists be true, should 
we not have every reason to expect that it would be a comparatively easy 
matter to demonstrate the various stages in the development of these gonidia 
from the lichen-hyphe? Fully formed gonidia have been repeatedly observed 
at the extremity of hyphal branches, and it has been inferred that they were 
developed in much the same way as are certain spores by the differentiation 
of a terminal cell; but intermediate stages have never been demonstrated to 
the satisfaction of first-class observers. We have no unquestioned proof that 
hyphe give rise to gonidia in this or in any other way. In the higher lichens, 
where the gonidia form a comparatively small part of the thallus, it was not 
unnatural to at first suppose that they were products of the hyphe. But with 
some of the more simply organized forms, such, for example, as the byssace- 
ous lichens, the case is far different, for we have here the gonidia forming 
much the larger and more important part of the thallus, so much so indeed 
that in places it requires some little care and rather a high power to even see 
the hyphe. Under such circumstances it would seem as if we had about 
as much reason to believe that the gonidia were produced by the hyphe as 
to suppose that the mistletoe gives rise to the oak tree on which it is found. 
Let us pass now from these structural considerations to the results of some 
experiments that have been tried in the germination of lichen spores and the 
culture of lichens. These experiments, performed by Rees, Treub, Bornet 
and Stahl, deserve a large share of our attention, but we have space for only 
a brief summary of the most important results which were obtained. 
