502 SUMMARY OF CURRENT RESEARCHES RELATING TO 



upon active nutrition, bright light, and moisture. In the cultures re- 

 productive organs were formed only in presence of peptone ; good 

 nutrition and aeration favoured the production of archegonia. The 

 second half of the paper treats of nutrition of mosses. 



Sporogenesis in Barbula muralis.* — E. Boucherie writes on the 

 cytologic phenomena of sporogenesis in Barhula muralis, and summing 

 up his results he finds the principal characters of the formation of 

 heterotypic chromosomes to be as follows : — (1) no pairing of filament 

 at prosynapsis and fragmentation of nucleolus ; (2) disappearance of 

 nucleolus at end of synapsis ; (3) transverse division of spireme pre- 

 ceding longitudinal division ; (4) formation of chromosomes in the 

 parasyndetic manner of Gregoire (longitudinal duplication) and not in 

 the metasyndetic manner (by " boucles.") The small size of the nuclei 

 and the rapid changes in some of the stages probably explains why so 

 little has been published about moss-nuclei. 



Thuidium recognitum and Allies. f — H. N. Dixon discusses Thu- 

 idium recognitum and its allies, and has been at considerable pains to 

 correlate the British with authentic continental plants. He is now able 

 to clear up several doubtful points, and to present in a simplified key 

 the microscopical characters by which the following may be recognized : 

 Thuidium tamariscinum, T. recognitum, T. delicatulum, T. Philiherti and 

 its var. pseudo-tamarisci. He also indicates their habitats. It is T. re- 

 cognition and T. Philiberti that have been misunderstood in this country. 



North American Bryophyta.J — A. Le Roy Andrews publishes a 

 monograph of the Sphagnacea^ of North and Central America — 39 

 species, with an elaborate key and adequate descriptions based on the 

 fine details of structure employed by modern authors in the discrimina- 

 tion of the species. Under S. suhsecundum is a synonymy of 36 reduced 

 species. 



E. G. Britton and J. T. Emerson§ give an account of the AndreaBaceas 

 in the same work, describing nine species of Andreaea. 



E. G. Britton takes charge of the Bryales, and with R. S. Williams || 

 has prepared a key to the families of acrocarpous mosses, five of which — 

 Archidiacese, Bruchiace^, Ditrichacet\3, Bryoxiphiacea3, Seligeriacea3 — 

 she treats in detail in the present instalment of the work. 



Philippine Mosses. If — V. F. Brotherus pubhshes a list of 207 

 mosses, his fourth contribution to the rich flora of the Philippine 

 Islands, and describes the characters of 32 new species and of a new 

 genus — Flagiotheciopsis — intermediate between PJagiothecium and Vesi- 

 cidarici, but entirely different from both in the structure of its peristome. 



* Comptes Kendus, clvi. (1913) pp. 1692-4. 



t Jourii. Bot., li. (1913) pp. 189-92. 



t North American Flora, xv. (New York, 1913) pp. 1-31. 



§ North American Flora, xv. (New York, 1913) pp. 33-9. 



II North American Flora, xv. (New Y'ork, 1913) pp. 41-75. 



t Philippine Journ. Sci., viii. (1913) pp. 65-98. 



