ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 65 



hardened protoplasm. The scarcity of records of raicrospore-formation 

 in plankton diatoms is explained by the author by the theory that it 

 occurs very rarely in a vegetative cell, but takes place normally at the 

 germination of the resting-spore, a process which has never yet been 

 watched. 



Algae of Suffolk and Norfolk.* — E. N. Bloomfield publishes lists 

 of the marine algae and fresh-water algae and Diatomaceae of Suffolk, 

 consisting principally of records made by Batters. The coast of Suffolk 

 is very unfavourable to the growth of algae, most of it being covered 

 with sand and shingle, while there are no hard rocks. Taking this 

 into account the list is a good one, consisting of 185 species. The 

 list of fresh-water algae and Diatomaceae, including both fresh-water 

 and marine species, is almost entirely derived from Henslow and Skep- 

 per's Suffolk Flora, 1860. A few additions were made by the late 

 W. West, junr. 



E. N. Bloomfield adds a short list of twenty-two marine species 

 taken from Batters' Catalogue of British Marine Algae, which have 

 been found on the coast of Norfolk, and are additional to those given in 

 H. D. Geldart's List of Norfolk Marine Algae published in these 

 Transactions, vol. iii. 



Fresh-water PlanktDn.f— R. Kolkwitz examines the connection 

 between the composition of water and the development of plankton, 

 as observed in the Lietzensee near Charlottenburg. After some general 

 remarks on the composition of the water of lakes and ponds, their 

 chemical analysis, and plankton, he describes the Lietzensee in some 

 detail. That water appears to be infested by Oscillatoria Agardhii at 

 certain seasons of the year, and the author gives a synopsis of its affini- 

 ties. The final chapter deals with the causes of the production of such 

 masses of Oscillatoria, after which the results of the paper are summed up. 



A. A. ElenkinJ studied the qualitative plankton of Lake Sseliger 

 for three months, from the end of May to the 20th of August, 1908. 

 The most important species are enumerated. The rare Atth&ya Zach- 

 ariasi J. Brun was present. The paper is in Russian, with a German 

 summary. 



Periodicity of Algae. § — W. Benecke has made experiments on the 

 periodicity of algae, having special regard to the formation of zygotes in 

 Spirogyra communis. In that species the resting-cells germinate in the 

 spring, and floating masses are formed. In summer these disappear, 

 zygospores having been formed by copulation in the meantime. In the 

 autumn growth is feeble, diminishing towards winter. There is no 

 more formation of zygotes. The experiments of the author go to show 

 that this periodicity is regulated by the quantity of nitrogenous com- 

 binations, be they nitrates or ammonium salts or organic combinations. 

 The possible cause for the diminution of these substances in the open 



* Trans. Norfolk and Norwich Nat. Soc, viii. (1908-9) pp. 768-83, 809-10. 



t Landw. Jahrb. Erganzungsb., v. (1909) pp. 449-72 (1 pi.). 



% Bull. Jard. Imp. Bot. St. Petersbourg, ix. (1909) pp. 15-21. 



§ Internat. Rev. Hydrobiol. u. Hydrogeograph. i. (1903) pp. 533-52. 



Feb. 16th, 19lo f 



