Physiologie. ~ Algae. 313 



Schleim ist, wie Verfasser zeigt, ein ge Wissermassen physiologisch 

 trockener Boden. Die Samen sonst rascher keimender Pflanzen 

 können nämlich nicht auf Mistelschleim keimen (auch wenn sie 

 darin versinken), weil sie dem Schleime das zur Keimung nötige 

 Wasser nicht zu entziehen vermögen Da bei der Mistel relativ 

 hohe Lichtintensitäten zur Keimung nötig sind, und da das Endo- 

 sperm und der Embryo Chlorophyll besitzen, rückt die Möglichkeit 

 in den Vordergrund, dass in der Aktivierung der COg- Assimilation 

 der Einfluss des Lichtes zu suchen sei. Verf. wird prüfen, ob auch 

 im COo-freien Räume, unter Beibehaltung der sonst zur raschesten 

 Keimung führenden Bedingungen, die Keimung erfolgt. — Die 

 Tafel zeigt photographische Aufnahmen keimender Mistelsamen in 

 natürlicher Grösse. Matouschek (Wien). 



Acton, E., On a new penetrating Alga. (The New Phytolo 

 gist. XV. 5-6. p. 97—102. 1 pl. and figs. London, July 1916.) 



The author gives a description of Govnontia Aegagropüae sp. 

 nov., a green alga found growing in the walls of dead cells of Cla- 

 dophora {Aegagropila) holsatica collected in Loch Kildona, He- 

 brides, and cultivated for some years in a pie-dish. The Gomontia 

 had also penetrated and spread beneath the glazed surface of the 

 pie-dish at numerous spots. The author describes and figures the 

 structure and ramification of the alga, and its means of multipli- 

 cation. She also discusses its systematic position, and reviews the 

 three genera of Döring algae: Gomontia, Tellamia and Foreliella. 

 Tellamia .she transfers to Endoderma. And Foreliella she unites with 

 Gomontia. E. S. Gepp. 



Acton, E., On the structure and origin of '^Cladophora 

 Balls." (The New Phytologist. XV. 1-2. p. 1-10. figs. March 1916.) 



Cladophora balls are found in certain lakes of Scotland and 

 Ireland and in other parts of Europe. Papers on them have been 

 published by F. Brand. C. Wesen berg-Lund and others. The 

 species which constitute the balls belong to the sub-genus Aegagro- 

 pila. The balls found in Loch Kildona, S. Uist, consist of C. 

 holsatica Kütz. They are composed of a densely felted thin living 

 outer-sphere surrounding a large cavity filled with plant-debris and 

 mud. The individuals composing the outer-sphere, having lost their 

 apical cells by attrition, emit many lateral branches, some of which 

 have been called "rhizoids" and others "cirrhoids", which act 

 respectively as haptera and clasping tendrils thus firmly interlocking 

 the feltwork of plants; other branches are "stolons" and act as 

 agents of propagation. Multiplication takes place only in vegative 

 ways, as the main cells slowly die off behind and set the branches 

 free. Sometimes isolated old axial cells rejuvenate in favourable 

 conditions, put out branches and initiate a new plant. Very thick- 

 walled hypnospores have been observed in the old balls which had 

 been in a laboratory for eight years; they burst or cast off the 

 thick wall and put a long "rhizoid", into which some of their pro- 

 toplast passes. The origin of the balls is described by Wesenberg- 

 Lund to be as foUows: A shallow part of the lake has its floor 

 clothed with a layer of small tufted separate individuals, which, 

 during the undulations set up by strong winds, hook on to one 

 another and gradually form packets, which again, being rolled by 

 waves and rubbed against the sandy floor, become rounded, and, 



