620 Algae. 



l.Phytoplanktonets Livskaar og Biologi samt de 

 i vore Farvande iagttagne P h y t o p 1 a n k t o n t o n - 

 ters Optraeden og Forekomst. [The Plankton of 

 the Danish Seas in the years 1898 — 1901; Phyto- 

 plankton and Protozoa. 1. The ConditionsofLife 

 and the ßiology of the Phytoplankton, and the 

 Distribution and Occurrence of the Phytoplank- 

 ton Organisms found in the Danish Seas]. Danske 

 Vidensk. Selsk. Skrifter, 7. Rgekke, naturvid.-mathem. Afd. IX. 2. 

 298 pp. 9 texttig. a. num. tab. Köbenhavn, 1913. Avec un resume 

 en fran^ais (66 pp.)) 

 This work is the main result of the author's more than decen- 

 nial studies on the marine phytoplankton of the Danish seas; it 

 gives really more than the title promises, as not only the phyto- 

 plankton of the years 1898—1901 is treated, but also that of later 

 years. After an introduction the following chapters are contained 

 in the book: 



I. Earlier Investigations, a historical review of earlier plankton 

 investigations in de Danish seas and of investigations in the adja- 

 cent seas by German, Swedish and Norwegian scientists. 



II. The conditions of life of the marine phj^toplankton with 

 special regard to the Danish seas and a short survey of the hy- 

 drography of these waters. This chapter contains the following 

 items: 1. The importance of the light for the ph^^'toplankton. 2. The 

 salinity and temperature of the water of the Danish seas. 3. The 

 gases dissolved in the water (oxygen, carbonic acid and nitrogen). 4. 

 The nutritive substances dissolved in the water; the contents of salts 

 of natrium, silica, phosphorus and nitrogen are especially discussed. 



III. Remarks on the Biology of the phytoplankton organisms. 

 A. The life-cycle and reproduction of the diatoms, Peridinians, 

 Flagellates, Halosphnera, Botryococciis and Schisophyceae . B. Adapta- 

 tions 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 one, respect. two seasonal flowering periods. 



IV. 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 depen- 

 dence of the hydrographical conditions. 145 species of phytoplankton 

 organisms are enumerated, and under each of them are given: its 

 regional distribution in the Danish seas; its seasonal occurrence; 

 the mean values of the salinity and temperature of the water where 

 it occurs in quantit}^; remarks on its distribution outside the Danish 

 seas. The seasonal and regional occurrences of the more important 

 species are illustrated on 75 tables in the text, giving the data from 

 9 Observation places in the Danish seas during two years (April 

 1899 — April 1901). A tabellaric summary recapitulates the following 

 biological characters for each organism: oceanic or neritic; holo- 

 planktonic or meroplanktonic; distribution (allogenetic or endoge- 

 nelic) in the different parts of the Danish seas; season for minimum 

 and maximum of occurrence, monacmic or diacmic; northern, 

 Southern or baltic distribution outside the Danish seas. 



The later part of the work contains a long list of literature 

 and 18 large plankton tables. 



In the French Resume most parts of chap. II and III and 

 the essen tial contents of chap. IV have been translated in orJer to 



