ZOOLOGY AND BOTANY, MICROSCOPY, ETC. (333 



Plankton and Seston.* — R. Kolkwitz discusses the vague usage of 

 the term plankton, which is sometimes made to cover detritus, sand, 

 remains of plants, etc., in fact anything collected by the nets or sieves. 

 He points out that this misuse of the word is not justified, and he defines 

 the word plankton as the natural affinity of those organisms whose 

 normal conditions of existence are found in open water, being carried 

 passively by currents, and unattached. Seston is the insoluble matter 

 which is capable of separation from water by means of filtration. 

 Plankton is therefore a constituent part of seston. 



Oceanography. t — Albert, Prince of Monaco, gave last April an 

 address to the Geographical Society in Vienna on the progress of 

 Oceanography. In the course of it he dealt with plankton, describing 

 it as the sport of winds and currents. It may be f onnd floating down 

 to 500 m. below the surface, and is the food of fishes which in their 

 turn are devoured by other fishes. Finally these latter perish and 

 become food for plankton. Thus the cycle is completed. In the case 

 of the whale there are no intermediate stages, the whale feeding directly 

 on plankton. 



Rhizosolenia victorise.:!: — B. Schroeder describes a new species of 

 fresh-water plankton from Lake Victoria Nyanza, Rhizosolenia victorise. 

 It is most nearly allied to R. morsa West. The author discusses the 

 genus and gives figures of the different species. 



Diatom Locomotion. § — T. C. Palmer has made further experiments 

 on the locomotion of diatoms, notably Navicida iridis, A^. socialis, 

 Nitzschia linearis, Surirella linearis, and >S. splendida. He describes 

 their movements along the lower surface of a cover-glass. Some speci- 

 mens were placed in an emulsion of Indian ink, and the results are 

 described. The author regards as impossible any general theory of 

 diatom motion based on inward or outward streams of gas, water, or 

 " gallerte," and expresses a renewed and greatly reinforced conviction 

 that moving protoplasm is the real and direct activator. 



Fresh-water Algae of the Antarctic.]] — F. E. Fritsch gives an 

 account of the fresh-water algse of the National Antarctic Expedition 

 under Captain Scott, 1902-4. The collections were made near Cape Adare 

 and McMurdo Sound. Of the 1)1 species observed, 52 belong to the 

 Myxophyceffi. [luge sheets of Phormidium and Lyngbya flourish in the 

 ice or water of ponds, and form a substratum for other blue-green algje 

 and Pleurococcffi. Only ?> genera of diatoms were found. The first 

 record of an Antarctic Desmid is made. Diagnoses of the new Myxo- 

 phyceae and diatoms are given, and critical remarks added ; and a 

 comparison is made with the floras of other Antarctic areas. 



* Ber. Deutsch. Bot. Gesell., xxx. (1912) pp. 334-46. 



t ]Mitt. k. k. Geogr. Gesell. Wien, Iv. (1912) pp. 178-195 (3 pis.). 



: Ber. Deutsch. Bot. Gesell., xxix. (1912) pp. 730-43. 



5 Proc. Delaware County Inst. Sci., vi. (1911) 7 pp. 



II Nat. Antarct. Exped. Brit. Mus. (Nat. Hist.), vi. (1912) 57 pp. (3 pis.). 



