Nelson: SOME ALG^E WHICH CAUSE "WATER BLOOM." 5!} 



The next reference to the subject was made in 1889 by Dr. 

 Wm. Trelease in an article, "The Working of the Madison 

 lakes, Wisconsin." He observed that every season a greenish- 

 yellow scum occurred in greater or less quantity on the lakes 

 during the hot part of the summer, after the weather had been 

 calm for a number of days in succession. When but little of 

 the scum-forming substance was present it appeared as fine 

 granules suspended in the water. Under the influence of a 

 gentle breeze, continuing in one direction for some time, these 

 particles were carried to the shore, accumulating to form a 

 slimy scum which quickly putrefied, giving off a disagreeable 

 odor. During the process the color of the mass changed to a 

 decided blue-green, which stained the pebbles, sticks, etc., over 

 which it was smeared. This material consisted mainly of 

 Clathrocystis aeruginosa (Kuetz.) Henfr. At different times 

 collections taken from the lakes proved to be, besides the 

 Clathrocystis, Anabcena flos-aquce (Lyngb.) Breb., A. mendota 

 and A. circinalis (Kuetz.) Rabenh. 



In August, 1897, Miss Elizabeth H.. Foss, a student in the 

 Botanical Department, collected Glczotrichia ptsum, floating 

 in large quantity on the surface of Lake Minnewaska, Glen- 

 wood, Minnesota, and on October 28 of the same year, Miss 

 M. G. Fanning and Mr. H. B. Humphrey found Anabczna 

 Jlos-aquce in abundance in Cedar lake, Hennepin county, 

 Minnesota. 



In November, 1899, Miss M. G. Fanning, then a student in 

 the Botanical Department, began making a study of the St. 

 Paul water supply. Of the "water bloom "-forming algae she 

 found specimens of Anabcena jlos-aquce (Lyngb.) Breb., and 

 Ccelosfh&rium kuetzingianum Naeg. 



In August, 1900, Professor Caswell A. Ballard, of Moorhead 

 Normal School, Moorhead, Minnesota, made a collection of a 

 "water bloom" form from one of the shallow lakes in the 

 depressions of the Fergus Falls moraine. A sample of the 

 material was sent to this department and it was determined to 

 be Aphanizomenon jlos-aquce (Linn.) Ralfs. (PI. XI V., Fig. /). 



Professor Ballard's attention was first called to this locality 

 by the report that several cattle in a pasture adjoining the shore 

 of the lake had died, apparently from poisoning. It was 

 observed that the lake was in a peculiar condition, the water 

 colored by a blue-green scum. A zone from twenty to twenty- 



