602 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Water-bloom.* — E. Wolf discusses the question of the " bloom " on 

 water as an important factor in the life-cycle of organic life. He divides 

 the organisms, which compose the bloom, into four classes, one of which 

 is Algae, i.e. Schizophyceas, Diatomaceae, and Chlorophycese, particularly 

 Desmidiacere. The colour of the bloom may be green, yellow, red, or 

 black, and the principal constituents of the bloom of each colour is given. 

 The thick slime of seas or lakes is also described : that of the Adriatic 

 being caused by Peridiniea?. As regards the role played by this water- 

 bloom in the general economy of nature, the author points out : — 1. The 

 organisms which form it possess the power of building up living ma- 

 terial from inorganic substance. 2. Their importance is universal, since 

 they are found in fresh and in sea water. 3. The thick covering is of 

 the greatest importance to their allies the bacteria, which work in the 

 mud, since sunlight hinders their activity, even killing them ; and it is 

 the bacteria which render the insoluble nitrogenous matter soluble and 

 useful to plants, as well as decomposing refuse. 4. The bloom also acts 

 as a purifier of water, destroying and using up decaying matter. 5. 

 Many of them are also guides to the connoisseur, their presence showing 

 at once whether the water is pure or foul. 6. By their extraordinary 

 power of reproduction they prevent any excess of dissolved material. In 

 the sea they are also assisted by the denitrification bacteria. 7. In con- 

 sequence of their large mass, they form the most abundant source of 

 nourishment to the animal life of the water : they are indispensable in 

 fish culture. 8. They enrich the water to a high degree with oxygen, 

 which benefits the fish. These considerations show clearly what a power- 

 ful factor the water-bloom is in nature. 



Marine Plankton.| — H. Lohmann has written three interesting 

 treatises on the subject of marine plankton in general, and throws light 

 on many vexed questions. He finds that many of the conclusions with 

 regard to the plankton-mass in any special region are often inaccurate, 

 since the mesh of the miller's gauze used (No. 20) is not fine enough to 

 insure the capture of the smallest organisms, and many of them slip 

 through and are lost. These are, of course, of the greatest importance 

 from the point of view of food-supply, and no summary is complete which 

 omits to take them into account. The author describes a much more 

 exhaustive method of catching plankton, by which nothing except 

 bacteria can escape ; and the result of his investigations in Kiel Bay 

 records many notable additions to the already known plankton-flora. 

 He criticises also the method employed for measuring the volume, and 

 describes his own improvements. He finds that from February to the 

 second half of August the plankton-mass steadily increases, and then 

 declines. The winter poverty is distinguished by a preponderance of 

 animals, and the summer richness by a preponderance of plants. The 

 supposed spring and autumn maxima, with the intermediate temporary 

 decline of summer, is shown to be due entirely to the failure of the nets 



• Ber. Senckenberg. Naturf. Gesell. Frankfurt a. M., 1908, pp. 575-7. 



t Wissenschaftl. Meersuntersuch. Abt. Kiel, x. (1908) pp. 122-370. Internat. 

 Revue d. gesamten Hydrobiologie u. Hydrograpbie, i. (1908) pp. 309-23. Natur- 

 wissenscbaftl. Wocbenscbrift, vii. n.s. (1908) pp. 801-10. 



