210 SUMMARY OF CURRENT RESEARCHES RELATING TO 



of Versailles, and he now publishes a list of the species he has found. 

 The tree forms are particularly well represented. In many cases the 

 author gives a complete description of the species ; nearly always he 

 gives the chemical reactions. There are 188 species and 48 forms or 

 varieties recorded. 



Research on Silicious Lichens.* — E. Stahlecker considers that the 

 form and anatomy of the lichen thallus are influenced by the chemical 

 constitution. On rocks composed of various constituents, the anatomi- 

 cal form of the plant is modified so that the hyphal layer in comparison 

 with the gonidial layer is stronger, especially where there is a larger 

 proportion of basic substance present, as for instance of lime. On 

 stratified rocks the silicious lichens grow most readily on the face of the 

 stone, at right angles to the strata. Fresh surfaces are favourite 

 localities, while weathered surfaces are avoided. The more acid the 

 substratum and the drier the fungus, the larger are the separate gonidia. 

 If the hyphse are stronger, then the gonidia are weaker. Lichens are 

 not found alone on the rocks, and therefore other factors influence their 

 development. 



Chemistry of Lichens.f — W. Zopf publishes a further contribution 

 on this subject. In Sphcerophorus collected from granite he had found 

 sphserophorin, sphserophoric acid, and fragilin. Another collection of 

 the same lichen from gneiss has enabled him to verify his previous 

 findings, and to describe more definitely the properties of the new 

 substances. From the thallus of Biatora mollis, collected on sandstone, 

 he has isolated diffusin acid, a substance similar to that which he found 

 in Platysma diffusum. A section of Gyrophora polyrrhiza becomes red 

 on the application of calcium chloride. Zopf finds that this is due to 

 the presence of lecanoric acid. He found, in addition, two other sub- 

 stances, umbilicar acid and gyrophor acid. He examined several other 

 lichens, and gives an account of the chemical constituents, and of their 

 colour reactions. 



Jaap, 0. — Einige Neuheiten fur die Flechtenflora Hamburgs. (Some new records, 

 from the lichen flora of Hamburg.) 



Allgem. Bot. Zeitschr., vi. (1905) pp. 150-1. 

 See also Bot. Centralbl., xcix. (1905) p. 549. 

 Kovae, P. — Beitrag zur Flechtenflora der TTmgebung Saars in Mahren. (Contribu- 

 tion to the lichen flora of the neighbourhood of Saars, in Mahren.) Russian. 

 S.A. Vestnik Klubu prirod. v. Prost. za rok, 1906 (1905) 

 8vo, 16 pp. See also Bot. Centralbl., 

 ci. (1906) p. 73. 



Wainio, E— Lichenes expeditionis G. Amdrup (1898-1902). 



[A contribution to our knowledge of Arctic lichens.] 



Meddel. om. Gronland, xxx. (1905) pp. 125-41. 

 See also Ann. MycoL, iii. (1905) pp. 489-90. 



* Inaug. Dissert. Stuttgart, 1905, 8vo, 44 pp., 1 pi. See also Ann. Mycol., iii. 

 (1905) p. 489. 



t Liebig's Ann. Chemie, cccxl. (1905) pp. 276-309. See also Bot. Centralbl., 

 xcix. (1905) pp. 588-9. 



