126 Wiscotisin Academy of Sciences, Arts and Letters. 



former genus was so abundant in the drinking water of Baltimore as to- 

 attract attention in midwinter, a few years since. ^ 



In closing, a word may be added concerning certain objects to some ex- 

 tent resembling green tomatoes, that have been noticed a number of times 

 on the bottom of the shallower parts of Third Lake, and of the larger pools 

 along the railroads. These are of rounded form, more or less lobed, and 

 of a pale bluish-green color. Their texture is rather firm, so that they 

 retain their form when taken from the water, though they may be easily 

 crushed to a formless mass of jelly, and when exposed to the air for a few- 

 days dry down into a thin film. 



- These bodies are colonies of Nostoc verrucosum Vauch. , one of the Nos- 

 tochinese, which is also found in the old world. Under the microscope 

 they are seen to consist of numerous contorted threads of a blueish-green 

 color, imbedded in a colorless jelly that holds them together and gives form 

 to the frond. 



The following list of papers referring to the water-bloom is confessedly 

 incomplete, but it will serve as a nucleus for other references. Only the 

 principal papers treating of the recurrence of bacteria in quantity have 

 been included; other references may be obtained from them. It should be 

 added that comparatively few of the papers referred to have much botani- 

 cal value. 



On the flora of ice and snow fields, in Alpine and Arctic regions, which 

 often produces striking color effects, see Wittrock, in Nordenskiold's Stu- 

 dien und Forschungen, veranl. d. meine Reisi im hohen Norden, Leipsic, 

 1885, where a bibliography of the subject is given. 



The diatomaceous origin of the discoloration of Arctic seas is discussed 

 by Eobert Brown, in the Transactions of the Botanical Society of Edin- 

 burgh, IX, 1867-8. 



Archer: An Oscillaria of Australian seas occurring in large quantities. 

 (Quart. Journ. Mic. Sci., XVII, 214; Bot. Johresb., VI, I, 403). 



Arthur: A supposed poisonous seaweed in the lakes of Minnesota. Proc 

 Am. Ass. Adv. Sc, 1883, XXXII, p. 305 — abstract. 



Arthur: Some Algge of Minnesota supposed to be poisonous. (Bull. Minn. 

 Acad. Nat. Sci., XI, 3; Fourth Rep. Univ. Minnesota, suppl. i, Rept. Dept. 

 Agr., 1887, 97. 



Arthur: Second Report on some Algee of Minnesota supposed to be poison- 

 ous. Fcurth Report Univ. of Minn., suppl. i, 109. 



Berkeley: Gleanings of British Algse. (Supplement to Sowerby's English 

 Botany, 1883). 



Bornet & Flahanet: Sur la determination des rivulaires qui forment des 

 fleurs d'eau. (Bull Soc. Bot. de France, 1884, 76.) 



1 As this is going to press, I notice a record of the occurrence of certain zoospores in such 

 quantity as to cause a water-bloom (De Toni, Shrovo Gion, Bot. Italiano, xx. 295), in which 

 references are given to several othar ItaUan papers on this subject. 



