Ludwig, Leuchten unsere Siisswasserperidinien V 295 



used: 1. one gram-molecule of phenol per gram-molecule of NaCl, 

 2. one gram-molecule of phenol to two gram-molecules of NaCl, 

 and 3. one gram molecule of phenol to three gram-molecules of 

 NaCl. The results obtained failed to show this action in any 

 distinct manner. The concentration-liraits marking thc survival 

 of the lupines as calculated on the basis of the phenol present 

 were 1/400 gram-molecule for the first and second Solutions and 

 somewhere between 1/400 and 1/800 gram-molecule per liter for 

 the third Solution. How much NaCl must be added in Order to 

 increase materially the toxic action of phenol toward the lupines 

 was not farther investigated. Krön ig and Paul were abk- to 

 observe tbis increase in working with bacteria ; in this case, 

 however, very much stronger Solutions of all kinds were used, 

 and it is not impossible that the concentration of the Solution may 

 in some way influence this action. 



Of the di-atomic phenols the isomers, pyrocatechol, resorcinol 

 and hydroquinone, were studied. 



Pvrocatechol, Ce H4 (ON) (OH) =^1:2. 



Leuchten unsere Süsswasserperidinien? 



Von 



Prof. Dr. F. Ludwig. 



In einem Aufsatz „die Welt im Wassertropfen", in Unter- 

 haltungen aus dem Gebiet der Natur, herausgegeben vom öster- 

 reichischen Lloyd in Triest, 1856, berichtet Ferdinand Cohn 

 auf p. 43 folgendermassen über ein leuchtendes Süsswasser 



