52 .MINNESOTA BOTANICAL STUDIES. 



Tetonka near the house of Mr. L. H. Bullis). Four calves 

 confined in a pasture near the house, with access to no water 

 but that of the lake were seen at noon apparently well, and at 

 2 P. M. were dead. On July 5, a number of cattle came down 

 the public road to the lake shore, that partly belonged to Mr. 

 Bullis and partly to neighbors. They were noticed between 8 

 and 9 A.M. and within an hour afterward three were dead, and 

 before noon three more. . . . The two young cattle were 

 examined shortly after death by Dr. E. B. Case and Dr. J. G. 

 Bemis, resident physicians. Nothing seemed to be abnormal 

 except the stomach, which appeared to have been affected by 

 the algae swallowed by the cattle. . . . The cattle did not 

 appear to suffer pain, but lay down as if enervated and soon 

 expired." The total number of animals thought to have died 

 from the same cause at this time included about twenty head of 

 stock, horses, cattle and hogs. 



The scum when examined was found to consist of minute balls 

 each made up of a dense colorless jelly in w r hich was embedded 

 a great number of dark-green, whip-like filaments, lying side 

 by side and radiating from a center. The larger ends were at 

 the center and the attenuated ends extended beyond the jelly. 

 Each filament was made jip of a row of pseudocysts enclosed 

 in a sheath and at the basal or inner end was attached a spherical 

 heterocyst. When decaying in masses the plant caused a 

 nauseating odor. The plant was determined by Dr. Farlow to 

 be Riv id aria flu it an s Cohn. 



Several weeks later Professor Arthur revisited Lake Tetonka. 

 Rivularia fluitans had disappeared, but in its place was another 

 scum-forming alga, intensely green in color, diffused through- 

 out the water and collected by the wind into a scum two or more 

 inches thick along the shore. Under the microscope it appeared 

 to consist of irregular colonies of minute plants. Each colony 

 was a mass of thin, colorless jelly containing many separate 

 oblong blue-geen cells placed some distance apart. This plant 

 is known as Ccvlosfih&rium kuctziiigianum Naeg. and is not 

 considered injurious. A small quantity of Anab&na circinalis 

 (Kuetz.) Rabenh. was also found associated with this plant. 

 Still another " water bloom " species found at this same time and 

 almost as abundant as the Calosfhairiiini was an alga named 

 Afthanizomenon flos-aquce (Linn.) Ralfs. It consisted of little 

 bundles of thin, delicate filaments. 



