500 SUMMARY OF CCJRRENT RESEARCHES RELATING TO 



• >ui the advantage of these movements to species which, like Euglma, 

 are often found in a confined space in very large numbers. A constant 

 circulation of them in all parts of the liquid is thus kept up, and they are 

 prevented from accumulating in such dense masses as would be detri- 

 mental to them. He suggests that some of the peculiar phenomena of 

 plankton distribution may be explained in this way. 



Mastigocoleus testarum.* — This alga, which hitherto has only been 

 known from salt water, is now recorded by G. A. Nadson from the river 

 Bug, not far from the town of Nikolajew in South Russia, where the 

 water is only sometimes brackish. Later he found it again in absolutely 

 fresh water in the rivers Msta (<louv. Nowgorod) and Narowa (Gouv. 

 St. Petersburg), not far from their cataracts, where the alga bores into 

 the limestone. This fresh-water form, which the author calls Mastigo- 

 coleus testarum Lagerh. var. aquse-dulcis, is of a blue-green colour and 

 its filaments are 6 ■ 5-7 • 5 /a in diameter. It is distinguished from the 

 typical salt-water form by the size and position of its heterocysts, which 

 barely or not at all exceed the diameter of the vegetative cells ; they have 

 an intercalary or terminal position and are very rarely lateral. Two other 

 chalk-boring species are often found with M. testarum, namely Hyella 

 fontana Hub. & Jad. and Plectonema terebrans Born. & Flahault. 



Injury to Water-cress Beds by Algae. | — The Board of Agriculture 

 have received specimens of Oscillatoria irrigua Kiitz., which was causing 

 great loss in some Hampshire water-cress beds, the alga having the 

 appearance of a black cobweb at the base of the plants, which degenerated 

 and died off. The algas may be eradicated by the use of copper sulphate, 

 one part to fifty million parts of water. The Board recommends that an 

 estimate of the amount of water in the beds be made, and then the copper 

 sulphate, enclosed in a piece of sacking, be slowly dragged through the 

 water until dissolved. 



Red-snow.}— J.Murray gives a short and interesting account of the 

 phenomenon known as red-snow, which, according to Schmarda, was 

 mentioned by Aristotle. Remarks are made on its geographical distri- 

 bution, which is world-wide in suitable localities— although the alga does 

 not appear to be of general occurrence in snowy regions. In the Ant- 

 arctic it is less common than in the North Polar region. The Shackleton 

 Expedition found no indubitable red-snow, but it found abundance of 

 red Rotifers, which increased with prodigious rapidity, and formed con- 

 spicuous blood-red stains on stones at the margins of lakes. It is now 

 admitted that while Sphserella nivalis may be the commonest cause of 

 red-snow, animals of various kinds may take part in producing the 

 phenomenon. 



Cell-division in Lyngbya.§ — W. H. Brown describes cell-division in 

 a marine species of Lyngbya (probably L. mqjuscula) occurring at Cold 

 Spring Harbor, Long Island. In a cell of this alga there is a large 



* Bull. Jard. Imp. Bot. St. Petersbourg, x. (1910) pp. 151-3. 

 t Journ. Board Agric, xvii. (1911) pp. 988-9. 

 % Knowledge, xxxiv. (1911) n.s. viii. pp. 109-10. 

 § Bot. Gaz., li. (1911) pp. 390-1. 



