452 SUMMARY OF CUKRENT RESEARCHES RELATING TO 



other species, Oscillatoria rubeacens occurs in masses in Lago Caldonazzo 

 and Zellersee in the winter, and Staurastrum paradox ittn in Lunzersee. 



Plankton of the Japanese Coasts.* — K. Okanmra enumerates sixty- 

 seven species of plankton micro-organisms, collected along the coast of 

 Prov. Tosa, in Shikoku, during September and October 1905, and on 

 the coast of Prov. Boshyu, near the entrance to the Gulf of Tokyo, in 

 May 1906. The material comprises a large number of the forms ^yhich 

 occur in the warm black current or " Kuroshiwo." All the species 

 recorded in the paper are figured, and a bibliography is added. In a 

 postscript the author gives a short note on the species of Ceratium, 

 comparing his views as to the specific value of certain characters with 

 the views of Schroder as expressed in his recent paper " Beitriige zur 

 Kenntniss des Phytoplanktons warmer Meere." Okaraura holds that 

 the general form and rigidity of hodj, as well as the angular flexure and 

 the direction of the horns at origin, are of much greater importance 

 specifically than the length of horns or the manner of curvature in their 

 course. 



New Diatom Structure.f^ — A. A. C. E. Merlin has succeeded in 

 finding a diatomic structure which has not hitherto been recorded, and 

 he describes the details observed in species of Jlelosira, Hyalodiscus, 

 Aidiscus, Coscinodiscus, and Triceratinm. The structure in question 

 consists of a very fine delicate lacework, which covers the central area of 

 some species, and the process caps of otliers. The author also took dark- 

 ground photographs of two diiferent forms of Trkeratium novce 

 zelandlae x 490. He describes his apparatus, lenses, etc. 



" Mare Sporco." | — A. Forti discusses the phenomenon known as 

 "Mare Sporco" (dirty sea), as observed in the Adriatic in 1905. He 

 reviews the opinions of authors as to its origin, rejecting all but micro- 

 biological explanations. He holds that the gelatinous colonies which 

 characterise this phenomenon may be of different sorts according to 

 the different places where it occurs. Roughly speaking, it is caused 

 by lower algaj, especially Bacillarieffi and Peridineaj, which in special 

 conditions, when the salinity of the sea diminishes, reproduce themselves 

 very rapidly in a vegetative manner ; later on, when they lose their 

 turgescence and the gas-vacuoles which serve to keep them afloat, they 

 sink to the bottom of the sea, and continue their life-history. He then 

 discusses the various causes which prevent the majority of these 

 organisms from attaining their complete development, e.g. the excessive 

 multiplication of hostile organisms, and particularly the infallible 

 degeneration of the species when vegetative reproduction is not 

 alternated with sexual reproduction. This tendency to degenerate in 

 the case of the phenomenon called " Mare Sporco " is represented first 

 by the dwarfing of the individuals, then by the impoverishment of the 

 siliceous substance, the increase of fragility, and probably also by the 

 attenuation of the vital functions, especially that of the chlorophyll, 

 which appears to be the main cause of the precipitation of the gelatinous 



* Annotationes Zoologicte Japonenses, vi., part 2 (1907) pp. 125-51 (4 pis.). 

 t Journ. Quekett Micr. Club, x. (1907) pp. 83-6. 

 X Nuov. Giorn. Bot. Ital., xiii. (1906) pp. 357-408. 



