572 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Lichens. 



Antarctic Lichens.* — Wainio has described the Lichens collected by 

 Racovitza during the expedition of the 'Belgica' to the Antarctic. 

 There are 79 species, of which 32 are new. The lists give a good 

 presentation of the Antarctic Lichen-flora. 



Formation of Soredia in Lichens.t — Georg Bilter criticises Nilson's 

 theories as to the significance of soredia formation. The latter holds 

 that they are caused by conditions of moisture, and cannot rank as 

 specific characters. Bilter passes in review various sorediate and non- 

 sorediate forms to prove the insufficiency of his theory. Lichens, for 

 instance, that live almost entirely in water, such as Lichina and others, 

 are non-sorediate. Nilson had stated that the development of soredia 

 was clue to the excessive growth of the alga, which burst the rind of the 

 thallus at the weakest spot — either at the edge or on weak portions of 

 the old thallus. Bilter points out how insufficient this explanation is, 

 as soredia appear unvaryingly in definite positions of certain Lichens. 

 Nilson's statement that isidia pass over into soredia also lacks proof. 

 Moisture is not the only condition that determines soredia formations. 

 Other factors have an important influence on their growth. 



Lichens of Alaska.:}: — Clara E. Cummings has determined the 

 Lichens of the Harriman expedition. Some 217 species were collected, 

 including 75 new to Alaska and two new to science. An historical 

 account of the records from Alaska is given in the preface, and a 

 review of the forms that occur most frequently. The flora is essentially 

 like that of other Northern regions. A large number of species of 

 such genera as Umbilicaria and Getraria have been found. A biblio- 

 graphy is published of the works consulted. 



Olivier, H. — Expose systematique et descriptions des Lichens de l'Ouest et du 

 Nord-Ouest de la France. Tom. ii. 1900-3. 



[This volume includes the Lecidese, Graphidese, Caliciacese, Verrucariae, 

 Collemacese, and the Parasites.] Paris, P. Klincksieck, 3 Rue Corneille. 



See also Hedwigia, xliii. (1904) p. 98. 



Zahlbbucknek, A.— Lichenes a el Damazio in montibus Serra do Ouro Preto 

 Brasiliae lecti in herb. Barbey-Boissier asservati. 



[The author describes some new forms of Parmelia. 



Bull. Herb. Boiss., se'r. 2, torn. iv. (1904) pp. 134-6. 

 See also Ann. My col, ii. (1904) p. 305. 



Schizophyta. 

 Schizomycetes. 



Bacterial Light and Photographic Plates.§— H. Molisch has 

 shown that the luminous colonies of Micrococcus phosphoreus can be 

 photographed after five minutes by their own light. The colonies then 



* Anvers (1903) 46 pp. (4 pis.). See also Ann. Mycol., ii. (1904) p. 305. 



t Hedsvigia, xliii. (1904) pp. 274-80. 



\ Alaska. V. Cryptogamic Botany. Doubleday, Page & Co., New York, 1904, 

 pp. 67-149 (2 pis.). 



§ Photogr. Rundschau, 1903, p. 10. See also Zeit. angew. Mikrosk., ix. (1903) 

 pp. 209-10. 



