22 



RECENT OBSERVATIONS ON COLLEMA, &c, 

 BRIEFLY CONSIDERED. 



By William Archer. 



As promised in the preceding number of this journal, I purpose 

 setting forth, as briefly as possible, the views of Schwendener and 

 Reess (page 11) on Collema, &c. Relinquishing the opinions sup- 

 ported by him in the earlier portions of his elaborate memoir on 

 the Lichen-thallus,* Schwendener, before he concludes, propounds 

 the doctrine that not only are the " Lichens" in question (the Colle- 

 macea3, alluded to by de Bary) no " Lichens," but that the whole class, 

 without excej)tion, fall under the same category ; that is to say, 

 that each is to be regarded as some one or other Algal-type which 

 has become, as it were, the home or residence of a parasitic growth 

 — the combination of the two being, in point of fact, the so-called 

 Lichen. His views on the question the author has given more at 

 large, in relation to various types, in a subsequent memoir, j" These 

 he states generally thus : — " As the result of my researches all 

 these growths [Lichens] are not simple plants, not individuals in 

 the ordinary sense of the word ; they are rather colonies, which 

 consist of hundreds and thousands of individuals, of which, how- 

 ever, one alone plays the master, whilst the rest, in perpetual cap- 

 tivity, prepare the nutriment for themselves and their master. 

 This master is a fungus of the class of Ascomycetes, a parasite 

 which is accustomed to live upon others' work : its slaves are green 

 alga3, which it has sought out, or indeed caught hold of, and com- 

 pelled into its service. It surrounds them, as a spider its prey, 

 with a fibrous net of narrow meshes, which is gradually converted 

 into an impenetrable covering ; but, whilst the spider sucks its prey 

 and leaves it lying dead, the fungus incites the algas found in its 

 net to more rapid activity — nay, to more vigorous increase. ... If 

 this mode of illustration be permissible, this fungus forms a remark- 

 able contrast not only to the predatory and murderous spider, but, 

 in quite an analogous way, to the vine and potato-fungus, as well as 

 all other fungi which vegetate in living organisms, and destroy 

 their host-plant, or host-animal, in the unequal struggle.''^ Such, 

 " popularly" expressed, is Schwendener's view as to " Lichens" at 

 large, which he now holds and supports. This quotation, I would 

 venture to suggest, would seem sufficiently to convey its own refu- 

 tation of the hypothesis, inasmuch as this assumed parasitic fungus 

 does not destroy or live upon its assumed algal-host. If the 

 ''parasite" cannot be a "fungus" it must be something else — 

 that something else no more nor less than the veritable " lichen," 

 though it may be, indeed, but in part represented; though, of 



# Dr. S. Schwendener — " UntersiichungenueberdenFlechten-thallus," in Prof. 

 Niigeli's " Beitriige zur wissensch. Botanik," Hft. 4, p. 195 (1868). 



f Dr. S. Schwendener — "Die Algentypen der Flechteugonidien," Basel, 1869. 

 X Schwendener — " Die Algentypen," etc., p. 3. 



