12 KAARE MÜNSTER STRØM. 



The method of germination was not observed, as I was 

 absent the summer when the growth of the colonies occurred. 



The few specimens of Coelastrum did not germinate, as 

 far as I could observe. 



It is a very noteworthy fact that the Alga had survived 

 twelve years in that condition, w^ithout losing the germinating 

 power. In such a state, the Pediastrum colonies may survive 

 very long time, even under severe conditions. 



This actual resting-stage has not been described before, as 

 far as I know, but similar stages, also with red-coloured contents 

 in the cells are well-known, and described in several papers. 



Professor Wjlle has mentioned the resting stage in his 

 supplement to the Chlorophyceœ, in „Die natürlichen Pflanzen- 

 familien", but he does not give any further description. 



The Botanic Museum of the Royal Fredericks University. 

 Christiania. December 10th, 1920. 



