ZOOLOGY AND BOTANY, MICROSCOPY, ETC 601 



Nanno-plankton of the Lake of Zug.* — K. Lantzsch publishes his 

 investigations on the nanno-plankton of the Lake of Zug, and its rela- 

 tion to the zoo-plankton. The nanno-plankton or centrifugal plankton 

 shows in summer and autumn a characteristic distribution in layers. 

 The lower limit at this season is about 80 m. deep. Here are found 

 the following : Ghroococcus, Gomphosphseria, Gyclotdla. Flagellates 

 [Ghromulina ovalis most common) appear to be limited to the upper 

 40-50 m. ; they show active photactive migrations. Towards the 

 autumn optimal zones of the components of the nanno-plankton become 

 more marked {Ghroococcus, Gomphosphseria, Binuclearia, and Gyclotella). 

 The determining factor seems to be the respective transparency and 

 quantity of light. The winter streamings obliterate these strata, and a 

 distribution is found in which there is no marked maximum from the 

 surface to the bottom (0-200 m.). In May there appears again the 

 summer depth-limit of 80 m. At the bottom was found a specific fauna, 

 which is discussed. The author suggests that centrifugal examination 

 might bring out new facts concerning Flagellates, Bacteria, and Ciliates. 

 A new species of Peridinieas is described. 



Plankton of the Adriatic.^ — J. Schiller writes on the smallest 

 plankton of the Adriatic, particularly the Coccolithophoridas. Besides 

 the phyto-plankton, the author found a rich nanno-plankton containing 

 Coccolithophoridas, Peridinieaj, SilicofiagellataB, Diatoms, Flagellatae, 

 Chlorophyceae. The last three groups are m'ore abundant in the cooler 

 than in the warmer seasons. The Coccolithophoridae, on the other hand, 

 have the same distribution throughout the year. The Peridinieae are 

 pronounced warm-water forms. The maximum development occurs in 

 May to June ; the minimum in December. It is always in the upper- 

 most strata that the richest development of the smallest plankton occurs. 

 Many species of Coccolithophoridge are able to withstand high and low 

 temperatures, strong cultivation, even a great fouling, and a high per- 

 centage of organic material ; even under these conditions they are able 

 to attain luxuriant growth. The Flagellataa are rich in eleven genera, 

 two being described as new. Many plankton animals live on the 

 Coccolithophoridae, and they form the most important builders of 

 sediment among the Adriatic organisms. 



Biological Conditions of the Adriatic Flora. $ — J. Schiller de- 

 scribes the biological conditions of the flora of the Adriatic. The mud 

 which covers the bottom is not suited for the establishment of alga?. 

 Only along the coasts is there a narrow border of ground covered with 

 pebbles, shells, etc., which bears a rich vegetation. Only in summer is 

 there a greater difference of temperature than 6°-7° between the water of 

 0-20 m. and below 20 in. Light is the most important factor for the 

 vertical distribution of the vegetation, as in the Gulf of Naples. The 



* Zeitschr. wiss. Zool., c. (1914) pp. 631-93 (6 figs.). See also Bot. Centralbl.', 

 cxxix. (1915) p. 251. 



t Ver. k.k. Zool. Bot. Gesell., lxiv. (1914) pp. 66-7. See also Bot. Centralbl. 

 cxxix. (1915) p. 252. 



% Ver. Gesell. Deutsch. Natur. u. Aerzte, ii. (1914) pp. 669-700. See also Bot. 

 Centralbl., cxxix. (1915) p. 275. 



Dec. loth, 1915 2 t 



