56 MINNESOTA BOTANICAL STUDIES. 



compounds play the leading part. The sanitary significance of 

 this matter is yet to be determined, but so far analysis indicates 

 that, in large quantities, the effect on general health would be 

 unfavorable. 



Summary. — Up to the present time there have been found, 

 in or near the state of Minnesota, seven kinds of blue-green 

 algae which form " water bloom." They are : 



Glceotrichia pisum (Ac) Thuret. (Rivularia jluitans Cohn.) 

 Ccclosphcerium kuetzingianum Naeg. 

 Aphanizometion Jlos-aqua: (Linn.) Ralfs. 

 Clathrocystis aeruginosa (Kuetz.) Henfr. 

 Anabama circinalls (Kuetz.) Rabenh. 

 Anabcena Jlos-aquce (Lyngb.) Breb. 

 Anabcena mendotce ( ?) 



In several instances it has been almost conclusively proved 

 that the presence of one or more of these species in drinking 

 water used by stock has caused fatal results. 



Bibliography. 



Arthur, J. C. Some algae of Minnesota supposed to be poisonous. 

 Bull. Minn. Acad. Nat. Sci. 2: (App.) 1-12. 31 My. 1SS3. 



Trelease, W. The working of the Madison lakes. Trans. Wis. Acad. 

 Sci. Art and Letters, 7: 1 21-129. pi. 10. 1SS9. 



Fanning, M. G. Observations on the algae of the St. Paul city water. 

 Minn. Bot. Studies, 2: 609-617. pi. 4.5, 46. 20 Jl. 1901. 



Jackson, D. D., and Ellms, J. W. On odors and tastes of surface 

 waters, with special reference to Anabcena, a microscopical organ- 

 ism found in water supplies of Massachusetts. Review of Am. 

 Chem. Research, 3: 1S97. 



Explanation of Plate XIV. (in Part). 



Figure 1. A "bundle" of trichomes of Aphanizomenon Jlos-aquce. 

 Drawn from Professor Ballard's collection, x 700. 



2. Anabcena circinalls. a, pseudocysts ; b, gonidium ; c, heterocyst, 



X 193- 



3. Anabcena Jlos-aquce. a, pseudocyst ; b, gonidium ; c, heterocyst, 



x 193. 



