^• S S SUMMAR1 OF CUKl.'KNT KKSKAKCHKS I.KI.ATI \<; TO 



hydrate solution. As controls he employed cultures in white light. In 

 ili' 1 dark they did Qot develop. The results of the experiments are 

 ■lest Til ied in detail. The cultures in the red-yellow light showed most 

 unfavourable development and organization : the cells lose their form 

 and the chromatophores become disorganized and drop to pieces. In 

 blue light the cultures are at first considerably behind those grown in 

 white light in strength of development and mass of production. P>ut 

 the older cultures (3 to 6 months) are but little behind the control 

 cultures. Qualitatively, as regards the morphology of the cell, its form, 

 structure, the colour of the chromatophore, the cultures in blue and 

 in wln'ie lighl show a great similarity to one another, and differ entirely 

 from those grown in red-yellow light. Continued culture in a blue 

 light shows a progressive improvement in the succeeding generations, 

 while the succeeding generations in red-yellow light show progressive 

 degeneration. 



Phytoplankton of the Zeller See.*— K. von Keissler reports on the 

 phytoplankton of the Zeller See in Salzburg, collected from June to 

 August 1909. After an introduction dealing with the shore-vegetation 

 he gives a list of the species observed in the plankton, which he designates 

 as of a general type. The phytoplankton plays a much greater part than 

 the zooplankton, and increases continuously "during the months named 

 in the number of individuals, while the zooplankton decreases. The 

 former contained twenty-two species. In August the number of species 

 became greatly reduced. Details of the composition are given. Com- 

 parison with the results of Brehm and Zederbauer show that the composi- 

 tion of the plankton of different years at the same time is not the same. 

 The amount of the plankton in the Zeller See seems to be larger in June 

 to August than that in other Alpine lakes, the maximum occurring in 

 June ; after which time the quantity declines slowly. 



Plankton from the Julischen Alps.f— K. von Keissler has examined 

 plankton from several lakes in the Julischen Alps, and reports on it. The 

 phytoplankton of the Veldes See is comparatively rich, but qualitatively 

 plays no more important part than the zooplankton. It is very poor in 

 species, despite the relatively high temperature. The absence of Ceratium 

 and Dmobryon is remarkable, as well as the very scarce occurrence of 

 diatoms. The composition of the plankton in June and Julv 1907 was 

 different from that in the same months in 1908. The Wocheiner See 

 showed very little plankton, the zooplankton being qualitatively greater 

 than the phytoplankton. Ceratium hirundinella was found. In the Lower 

 Weissenf elder See the samples showed hardly any but phytoplankton, 

 winch is, however, not rich and consists almost" entirely of diatoms. 

 Dmobryon, Fragillaria, and Ceratium are almost wholly wanting. The 

 Upper Weissenf elder See is very cold, and has but a poor plankton. 

 JVostoc cceruhum was found, but is probably to be reckoned as a chance 

 escape from the bank flora. 



wJ/rSl^'u 101, UU , d Pla n k tonkunde, v. (1910) pp. 339-50; see also Hea- 

 wigia, 1. (1910) Beibl., pp. (149)-(150). 



• Tom. cit., pp. 351-64; see also Hedwigia, 1. (1910) Beibl., pp. (150)-(151). 



