102 SUMMARY OF CURRENT RESEARCHES RELATING TO 



threads become older, they increase in thickness, thus showing that 

 they are not merely temporary or effete structures. On the stouter 

 connecting-cords a sort of ring or collar is developed at about the 

 middle point, and over this is stretched, in some cases, a delicate 

 diaphragm. The behaviour of both rings and diaphragm, when treated 

 with microchemical reagents, is similar to that of ordinary protoplasm. 



Distribution of AlgSB in the Bay of Naples.* — G. Berthold finds 

 that if, in the algse growing in the Bay of Naples, those species are 

 separated the habitat of which is above low-water mark, and those 

 which require strong currents, the great majority of the 180 to 200 

 species which remain are not confined to particular zones of depth. 

 The species found in the zone between ebb and flow are usually 

 peculiar to that habitat, or at all events do not thrive in greater 

 depths. To this class belong Bangia, Nenialeon, and Gelidium crinale. 

 Some species thrive best in strong currents ; Corallina is especially 

 partial to the zone of breakers. Stagnation of the water greatly 

 diminishes the number of species; and some, in consequence, are 

 entirely wanting at considerable depths. The presence of diffused 

 light in the water is extremely important for the life of algfe ; the 

 minimum intensity at which they can thrive lies at but a small depth 

 below the surface. Those species which grow in shady places, like 

 marine grottoes, are in general found only near their entrances. The 

 Florideae are found especially where the light is diffused, the greater 

 number of brown algse, with a few Florideae and Chlorosporeae, in 

 localities exposed to the direct light of the sun. 



Algse of Bohemia."!" — A. Hansgirg gives a detailed account of the 

 algae of Bohemia, with reference both to their classification and their 

 biology. The mode of life of Le^totlirix rigidula Kiitz. is especially 

 described in detail. 



Fossil Alga, I — Under the name Byihotrephis devonica, C. J. 

 Andra describes a new alga, the remains of which he finds in the 

 " Hunsriickschiefer," belonging to the Devonian formation. 



New Genera of Alg8e.§ — A. Borzi describes several new genera 

 of alg^e, as under, viz. : — 



Leptosira. — The only species, L. Mediciana, occurs among cultures 

 of fresh-water algse from bogs on Etna. It forms minute rounded 

 green tufts composed of a number of dichotomously branched arms. 

 The cells are oblong, and with very delicate cell-wall. All the cells 

 can become zoosporangia. They swell into a spherical form, and the 

 numerous zoospores escape through a hole in the side of the mother- 

 cell. They are at first all inclosed in a common envelope, which 



* MT. Zool. Station Neapel, iii. (1882) pp. 393-536 (3 pis.). 



t SB. Bohm. Gesell. Wissensch., 1883. See Bot. Oentralbl., xvi. (1883) 

 p. 33. 



J Verhandl. Naturli. Ver. Preuss. Rheinlande u. Westfalen, ix. (1882) pp. 

 110-3. 



§ Borzi, A., 'Studi Algologici,' 117 pp. (9 pis.) Messina, 1883. See Bot. 

 Centralbl., xvi. (1883) pp. 66-75. 



