'220 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Lichens. 

 (By A. Lorrain Smith, F.L.S.) 



Text-book of Lichens.* —A. Zahlbriickner has just issued the last 

 fascicle dealing with lichens in the Pficmzmfamilien. It concludes the 

 Ascolichenes, and gives an account of the Hynienolichenes. The latter 

 include only the three genera Cora, Gorella and Dictyonema, all of 

 these containing only tropical or subtropical species in which the 

 symbiont is a cyanophyceous alga, and the fructification that of a 

 Basidiomycete. An index of the genera completes the volume. 



Noteworthy Lichens.! — E. Senft has examined a peculiar growth 

 found by A. Zahlbriickner on the thallus of Physma dalmaticum. It 

 arose either intercalary on hyphae of the thallus or terminal on these 

 hyphae. There was no cellulose reaction, and the author considered it 

 to be probably a change in the hyphae due to an enzyme, whereby they 

 were rendered mucilaginous. 



Dispersal of Lichens.} — P. Beckman has considered the case of 

 those crustaceous rock lichens that have neither soredia nor hymenial 

 gonidia, such as Gasparrinia murorum, Lecanora sordida, Hmnatomma 

 ventosum, etc. The spores must be chief agents in the spread of these 

 forms, but the mode of growth of the thallus must also play a part ; 

 the areolae into which they are divided tend to become further apart, 

 and in time, by weather-action, to become loosened from the substratum 

 and carried about by the wind. All these scattered areolae represent 

 one individual plant. In the case of several species of Rhizocarpon 

 with a creeping and spreading hypothallus, the spores start new 

 individuals at different centres which tend to meet each other, thus 

 presenting a decussated thallus. The thallus of these forms is also 

 often cracked, but the cracking serves probably only for aeration and 

 not for dispersal. 



Lichen Constituents. § — 0. Hesse has examined the chemical con- 

 stituents of a large series of lichens, a continuation of previous work 

 in the same field. He found a new acid in Usnea articulata, which he 

 designates articulat-acid, and two in Ramalina armorka, armorica-acid 

 and armor-acid. He found also new substances in the brightly -coloured 

 Tornabenia (Physcia) chrysophthalma and T. flavicans. Other lichens 

 yielded various acids already known. 



Brown ParmeliaB.|| — F. Rosendahl has brought his anatomical study 

 of the group to bear on their systematic position, and at the end of his 



* Engler and Prantl's Nat. Pflanzenfamilien, Leipzig: W. Engelmann, i. 

 Abt. 1, lief. 230 (1907) pp. 193-249 (24 figs.). 



t SB. k. Akad. Wiss. Wien Math.-Nat. Kl., cxvi., Abt. 1 (1907) pp. 429-38 

 (1 pi.). See also Bot. Centralbl., cv. (1907) p. 630. 



\ Engler, Bot. Jabrb., xxxviii. (1907) Beibl., pp. 1-72 (10 figs.). See also Ann. 

 MycoL.v. (1907) pp. 459-60. 



§ Journ. prakt. Cbemie, Neue Folge, lxxvi. (1907) pp. 1-57. See also Bot. 

 Centralbl., cv. (1907) pp. 628-9. 



|| Nova Acta Abh. k. Leop.-Car. Deutscb. Akad. Nat., lxxxvii. (1907) pp. 403-59 

 (4 pis.). 



