496 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Sphagnum in Sweden.* -E. Melin publishes the result of his 

 sphagnological studies in Tiveden, in South Sweden. He divides Ins 

 matter into four sections. 1. Survey of the most important Sphagnum- 

 associations in Tiveden. 2. H. Paul's division of the Sphagna. ■'>. The 

 question of whether the hyaline cells act as an apparatus for capturing 

 food-stuffs. This he illustrates with a number of figures of sections of 

 stem and leaf. 4. The Sphagnum-fioTa of Tiveden — thirty-four species. 

 He also provides a map to show the distribution of the following 

 species in Sweden, Norway, and Denmark : — S. Lindbergii, S. Wulfianum, 

 S. Gravetii, S. pulchrum. 



Thallophyta. 



Algae. 

 (By Mrs. E. S. Gepp.) 



Plankton of the Danish Seas.t — C. H. Ostenfeld publishes an 

 account of the plankton of the Danish Seas in the years 1898-1901 — 

 Phytoplankton and Protozoa. It is the main result of more than ten 

 years' study on the subject, and gives really more than the title indicates, 

 the plankton of later years being also treated . The first chapter, follow- 

 ing an Introduction, is a historical review of earlier plankton investiga- 

 tions in Danish seas, and in adjacent seas, by German, Swedish, and 

 Norwegian scientists. Chapter n. describes the conditions of life of the 

 marine phytoplankton, with special regard to the Danish seas, and 

 gives a short survey of the hydrography of these waters. Chapter in. 

 discusses the biology of the plankton organisms : A. The life-cycle and 

 reproduction of the Diatoms, Peridinieas, Flagellatse, Halosphsera, 

 Botryococcus, and Schizophyceas. B. Adaptations to the planktonic 

 life. C. The periodical occurrence of the plankton organisms ; plankton 

 communities. Here the new terms monacmic and diacmic are proposed 

 for plankton organisms having respectively one, or two, seasonal periods. 

 Chapter iv. contains an enumeration of the species of phytoplankton 

 organisms observed in the Danish seas in 1898-1901, together with 

 remarks on their seasonal occurrence, their distribution, and their 

 dependence on hydrographical conditions. The number of species 

 enumerated is 145, and under each of these is given its regional dis- 

 tribution in the Danish seas ; its seasonal occurrence ; the mean values 

 of the salinity and temperature of the water where it occurs in quantity ; 

 remarks on its distribution outside the Danish seas. A series of tables 

 show the seasonal and regional occurrences of the more important species ; 

 and a tabular summary recapitulates the following biological characters 

 for each organism : oceanic or neritic ; holoplanktonic or meroplank- 

 tonic ; distribution in the Danish seas; season for minimum or maximum 

 occurrence ; northern, southern, or Baltic distribution outside the 

 Danish seas. A bibliography is appended. A resume is published in 



* Arkiv. for Botanik, xiii. (1913) No. 9, 59 pp. (map and figs.). 

 % Dansk. Vidensk. Selsk. Skrift., ix. (1913) 298 pp. (pis. and figs.). French 

 resume, 66 pp. 



