Notes and Comment. 



1S9 



it is rare to find ponds the plankton of which consists mainly of 

 Diatoms. Very characteristic of the ponds are the numerous 

 Protococcoideae, also some Conjugatae are often found. In 

 spring and autumn large maxima are formed by Flagellates, 

 which are perhaps the most dominant forms. 



6. Plankton of the artificial marl pits, which are very 

 numerous in Denmark, consists nearly of zooplankton alone, 

 phytoplankton being practically absent, especially in newly 

 dug pits. 



7. The plankton of bogs is characterized by the large max- 

 ima of Flagellates, while Chlorophyceae are nearly absent and 

 Diatoms play a secondary part. 



8. The plankton of very shallow pools of drying up rain- 

 water is very little known in Denmark; the phytoplankton con- 

 sists of Flagellates and small Protococcoideae. 



9. The plankton of pools with manured water is quite 

 peculiar; among organisms with chlorophyll Euglaena is an in- 

 habitant of this association. 



NOTES AND COMMENT. 

 Readers of the Plant World have noted that the sections 

 devoted to Books and Current Literature and to Notes and Com- 

 ment have recently been allotted somewhat more space and that 

 a greater variety of topics have received attention. As this has 

 appeared to meet with approval it is proposed to continue the 

 arrangement and, if possible, to enlist the cooperation of working 

 botanists who may be willing to contribute notes of whatever 

 kind that are indicative of actual progress within their sphere of 

 activity and observation. As in preceding numbers, these 

 notes will be as informal as possible. Facts that have become 

 common property will be given brief mention, often without 

 reference to authority. The Botanisches Centralblatt ill be 

 drawn upon for items of interest at home and abroad, and work 

 of American botanists now in progress will be given due attention 

 as far as it is possible to obtain reports. Discussion and criticism 

 will be welcomed in so far as they are of a scientific rather than 

 personal nature. Botanists everywhere are invited to contrib- 

 ute notes, suggestions, plans of work, in short anything by which 

 other botanists and teachers of botanv are likelv to be aided. 



