ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 75 



spireme-thread. In the prophase of the heterotypic nuclear division all 

 chromatin-granules close up together (synapsis) and appear in the nu- 

 cleolus and around it united into groups of four(?). Here also no 

 spireme is formed. 6. The walls of the tetraspores show extremely fine 

 plasmoderm-Iike pores, recognizable even in the tetrad. 7. In respect 

 of the number of chromosomes and the reduction, the tetrasporic plant 

 of B. sanguinea is the sporophyte and the reproductive plant is the gamo- 

 phyte ; and between these, as we must agree, an alternation of generations 

 takes place according to the theory propounded by Yamanouchi. 



Unicellular Hairs of Floridese.* — L. K. Rosenvinge publishes some 

 remarks on the hyaline unicellular hairs of the Floridea3. There are 

 two kinds of hairs— (1) unicellular, (2) pluricellular and branched. The 

 latter are characteristic of the large family Rhodomelacese, and are 

 known as " Haarsprosse," trichoblasts. The unicellular hairs are but 

 little known, yet they have been treated of by Thuret in 1878, and by 

 Berthold in 1882. Rosenvinge describes the occurrence of unicellular 

 hairs on Danish species of Floridese, and shows that they are found in 

 all the families and in half of the species. He then treats of the struc- 

 ture and' development of these hairs ; of their position ; of their appear- 

 ance in relation to the season and the depth ; of their function. In 

 function they may possibly be protective, or they may be absorptive, 

 or they may have some special use. This is at present ol)SCure. 



Oceanic Algology.t — A. Mazza continues his studies of oceanic 

 algology, and treats of the genera Antithamnion (nine species) and Platy- 

 thamnion (one species). 



Algae of Pianosa.l — A. Forti and A. Mazza give an account of the 

 marine, fresh-water, and terrestrial algfe of the island of Pianosa in 

 the Tyrrhene Sea. Their list includes 19 Floridea\ 11 Fucoideai, 

 7 Chlorophyceee, 19 Diatomaces, 10 Myxophyceae, and 1 Chara. It is 

 a contribution to Sommier's natural history of the island. 



Algae of Iceland. § — H. Jonsson gives a general account of the algal 

 vegetation of Iceland, and of the vegetative conditions of the Icelandic 

 coast. The contents of the paper are as follows : — 1. External factors, 

 such as tides, temperature of the sea, etc. 2. Horizontal distribution, 

 and the composition of the flora, which is largely boreal and sul)- 

 antarctic. 3. Relations to neighbouring floras. 4. Vertical distribu- 

 tion ; the lowest limit is reached at a depth of -40 m. as a rule ; but 

 Lithothamnium is found at a depth of 60 to 80 m. 5. Algal associations. 

 0, Differences between east and south Iceland. 



Old Hortus Siccus. Ij—G. B. De Toni gives an account of an old 

 hortus siccus of marine organisms, bearing the title : — " Series zoophy- 

 torum maris & sinus Gibraltarici. Gibraltar 1797. Botanico indefesso 



* Extract from Biol. Arbeider tilegn. E. Warming (1911) pp. 203-216 (figs.), 

 t Nuov. Notar., xxii. (1911) pp. 157-71. 



X S. Sommier, 1' leola Pianosa. Firenze : Ricci e Pellas (1910) 177 pp.^ 

 § Om Algevegetationen ved Islands Kyster. Doktordissertation. Kopen- 

 hagen (1910) 104 pp. (pis. and figs.). 



,; Nuov. Notar., xxii. (1911) pp. 172-8. 



