THE DUAL-LICHEN HYPOTHESIS. 
105 
with stamens and pistil, then in course of time, as the ovary 
matures, seed in all respects identical with that from which the 
plant originally developed ; in such a case we should certainly 
conclude that the plant under examination is a complete and perfect 
plant, possessed of all the essentials for the reproduction of its 
species. 
If instead of following the plant through all its stages, we bring 
experience to our aid in judgingof probabilities, we examine aplant 
possessed of root, stem, leaves, and complete reproductive organs, 
bearing perfect seeds, we may safely conclude that we are examin- 
ing a complete and perfect plant. All these organs we know by 
experience are not essential to the perfection of fruit in all plants, 
in some the stem will be almost obsolete, as in the daisy, or without 
true leaves, butwith leaves and stem fused into a foliaceous expan- 
sion, as in the duckweed ; and yet there will be no suspicion that the 
plant is incapable of reproducing its species, thus proving itself a 
perfect plant (using the term perfect, as in the sense of complete- 
ness). Hence we may conclude that if a plant is capable of repro- 
ducing its species, when excluded from all external influences, by 
means of its own proper organs, we may assume such an one to be a 
complete plant, whatever modifications in structure may be present, 
and whatever secondary organs may be absent. Such plants, how- 
ever minute or simple in structure, are entitled to rank as autono- 
mous plants. 
The spore of a species of Peziza germinates, producing root-like 
fibrils of great delicacy, and upon these arise small globose bodies, 
which as they grow become perforated at the apex, ultimately 
expanding into a cup, which completes the vegetation of the little 
plant ; it is simply a minute fleshy cup, with a fibrous base, by 
means of which it is attached to the matrix. A section of this 
cup exhibits the reproductive bodies, the ova (if such a term may 
be permitted) contained in elongated tubes, closed at the apex, and 
packed side by side. These spores when matured, are capable of 
reproducing the form and character of the parent. Yet simple as 
such a plant may be, no one has yet raised a doubt as to its being 
a complete plant. 
Another simple plant, with similar cup-shaped organs, or recep- 
tacles, enclosing similar reproductive bodies, contained also in 
cylindrical tubes, but with other organs superadded, such as a 
foliaceous expansion, analogous to leaf and stem, or it may be some 
other bodies characteristic of the group to which it belongs ; and at 
once analogy leads us to the conclusion that this also represents a 
complete plant. 
If we concede that the Duckweed is a perfect plant, and the 
Peziza also a perfect plant, then also the Lichen must be a perfect 
plant. 
Are Lichens ( exclusive of their Gonidia') identical with Fungi ? 
The hypothesis in question assumes that the lichen consists of a 
fungus, enclosing certain foreign bodies, called gonidia. Hence 
