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THE AMERICAN MONTHLY [September, 



few years ago, and now well known 

 amongst lichenologists as the 

 " Schwendenerian theory." Briefly 

 expressed, this theory is that — Lich- 

 ens are not autonomous plants ; not 

 individuals, in the ordinary sense of 

 the word, but a compound of fila- 

 men ous hyphse of the fungi and the 

 green matter of the algae. The me- 

 dulla of the Lichen is the supposed 

 fungus ; and the colored gonidia 

 which are found in Lichens, the sup- 

 posed algae. The fungus is said to 

 be parasitic upon the green cells of 

 the algae, holding them as prisoners 

 and slaves, and by their activity 

 nourishing its own growth. We can- 

 not discuss this theory here ; nor 

 would it be prudent to enter into it 

 in any large way. But, we may re- 

 mark upon it, that, supposing 

 Schwendener's hypothesis were true, 

 still, the Lichen would be a distinct 

 plant, and would have a claim to be 

 so recognized. Inasmuch, as the 

 supposed fungi and algae combined 

 produce a plant differing from either 

 of themselves, and which could not 

 exist if they were separate ; also, if 

 either the green cells, or the hypha, 

 produce the one or the other, then 

 they are no longer either algae or 

 fungi ; for a true alga does not grow 

 fungal hyphae, nor does a true fungus 

 produce green algal cells. But the 

 Lichen has its own independent 

 characteristics, independent either of 

 fungi or algae. It has its own distinct 

 and definite forms, its own habits of 

 life, its own organs of self-propa- 

 gation ; and if fungi or algse were by 

 some means obliterated from the 

 earth, so far as their presence is con- 

 cerned. Lichens would continue to 

 flourish all the same. But further, 

 most or all our leading lichenologists 

 are against this dual-hypothesis of 

 Schwendener. This does not prove 

 the theory untrue, we know, but it is 

 a fact which carries great weight, 

 when we reflect that they who have 

 made Lichens a special and a life- 

 study, must be allowed to be as well 

 or better acquainted with them than 



men whose investigations have for 

 their object merely the founding or 

 support of a theory. Dr. Nylander, 

 than whom does not live a greater 

 authority on Lichens, by his own in- 

 vestigations and from his own know- 

 ledge, has repeatedly shown the ab- 

 surdity of Schwendener's theory ; and 

 he speaks of it as "that hypothesis 

 which none indeed but tyros can pa- 

 tronize," "An hypothesis informal 

 and absurd, supported by no serious 

 observations." As to how Lichens 

 shall be regarded anent this hypothe- 

 sis, Mr. Bentham considers that 

 "whatever be the result, the group 

 of Lichens is so distinct in its nega- 

 tive characters, and at the same time 

 so extensive and varid a one, that it 

 seems more methodical to treat it, as 

 heretofore, as a distinct class, than 

 to absorb it in that of fungi, notwith- 

 standing the close affinity shown by 

 its reproductive organs." In as brief 

 a manner as is consistent with clear- 

 ness, we shall now endeavor to give 

 some description of the Lichen or- 

 ganism, with some reference to its 

 habits and uses ; and then drop a 

 few hints relative to the study of 

 this group of plants. The Lichen, 

 as a plant, has no axis, either 

 ascending or descending ; no branches 

 or leaves in the same sense as phen- 

 ogamous plants. Its nearest approach 

 to a leaf can only be called a lobed 

 or laciniated frond. Its vegetative 

 or expansive portion is denominated 

 a thallus. (Gr. thallos, a young shoot or 

 frond. ) The thallus may be said to com- 

 prehend the whole plant, inasmuch as 

 it contains within its tissues, or bears 

 upon its surface the reproductive or- 

 gans, both male and female, with 

 their fruit. The form which the thal- 

 lus assumes in growth is very varia- 

 ble. So is its consistence, size and 

 color. It will sometimes expand 

 to one or two feet in diameter ; 

 while, in other forms, it will present 

 a small gray or colored spot ; and 

 often nothing but the fruit will be 

 seen, the thallus being evanescent. 

 The typical forms of the thallus are 



