354 SUMMARY OF CURRENT RESEARCHES RELATING TO 



would be equally favourable for both partners, we should get mutualism ; 

 but the conditions always favour only one, and it gains an advantage 

 and preys upon its symbionts. Unless the balance is redressed, the 

 complete destruction of the weaker is certain, and is followed by the 

 death also of the stronger. He compares the symbiotic life to a pair of 

 balances, of which the scales move up and down, but are rarely hori- 

 zontal. This is true also of parasitism ; it is a balance between host 

 and parasite which is to overcome the other. 



Anatomy of Collema.* — Hue has examined microscopically the 

 thallus and fruits of a large number of CoUemas, and publishes an 

 account of his observations. He gives measurements of hyphae and 

 gonidia, describing the position of these constituents. The form and 

 dimensions of the apothecia, spores, paraphyses, etc., are also carefully 

 set down. Several new species are described, and others critically 

 examined. 



Parmelia physodes.t — J. A. Vereitinoff distinguishes three distinct 

 varieties in this species, which he describes according to the form and 

 position of the soredia. In the typical form the outbursts of soredia 

 occur in incisions at the edge of the thallus. In another they take 

 the form of protuberances of a helmet shape. In still another variety 

 the soredia are developed on the surface of the thallus. The author 

 found no transition forms between P. physodes and the variety tuhulosa. 

 He is inclined to give the latter specific rank. 



Cup I NO, LuiGi — Un manipola di Licheni dei dintorni di Napoli. (A few lichens 

 from the neighbourhood of Naples.) 



[A small collection of lichens made by Cufino himself.] 



Malpighia, xx. (1906) pp. 339-44. 



Paul, Josef — Zur Flechtenflora von Yahren und Osterr-ScMesien. (The lichen- 

 flora of Mahren and Austrian Silesia.) 



[The writer does not claim completeness for his list, but prints it as an 

 incitement to further effort.] 



Verh. Natur. Ver. BrUnn, 1905 (1906) pp. 80-90. 

 Wainio, Ed. a. — Lichenes novi rarioresque. (New and rare lichens.) 



[A number of new species collected by J. Schmidt in the East are described.] 



Hedwigia, xlvi. (1907) pp. 168-81. 



Mycetozoa. 



(By A. LoBBAiN Smith.) 



Studies in Myxomycetes.J — This sixth contribution by E. Jahn on 

 the subject of Mycetozoa is devoted to a study of nuclear fusion and 

 reduction divisions. Heleue KranzHn, in her work on the development 

 of the sporangia of Trichia and Arcyria, had noted the presence of 

 degenerate nuclei, and Jahn has followed up the history of these nuclei. 

 They are noticeable in a very early stage by their smaller size. The 

 large nuclei present in the sporangia had arisen from the fusion of two 

 ordinary nuclei ; the degenerate nuclei were those that had been left 



* Journ. de Bot., xx. (1966) pp. 77-96. 



t Bull. Jard. Imp. Bot. St. P^tersbourg, xi. (1906) pp. 128-32. See also- 

 Hedwigia, xlvi. (1907) Beibl., p. 61. 



X Ber. Deutsch. Bot. Gesell., xxv. (1907) pp. 23-5. 



