424 MIXXESOTA BOTAXICAL STUDIES 



CJilorophyceae 

 Spirogyra sp. 

 Eudorina elegaus Ehr. 

 Pandorina moritm (Mull.) Bory. 

 Pcdiastruw duplex Meyen. 

 Staurastruui sp. 



Diatomaceac 



Stepliaiiodlscifs uiagarac Ehr. 



Syncdra pulchcUa (Ralfs.) Kg. 



Fragilaria capucina Desmaz. 



Asterionella fonnosa Hass. 



Cydotella com fa (Ehr.) Kg. 



Melosira grannlata (Ehr.) Ralfs. 

 Cyanophyceae 



Anahaena oscillarioides Bory. 



Anahacna flos-aquae (Lyngb.) Brcb. 



Clathrocystis aeruginosa (Kuetziug) Henfrey 



Coelosphaerium knetzingianmn Naegeli. 



Aphauizomenon flos-aquae (Linn.) Ralfs. 



Rivularia echinulata (Smith) Born, and Flah. 

 Protozoa 



Ceratiiim longicorne Carter 



Dinohr\'on scrtularia Ehr. 



Uroglena volvox Ehr. 



Vorticella communis Ehr. 

 From observations made on the above-mentioned forms, the re- 

 sults of which are for the most part shown in accompanying dia- 

 grams or figures, the following conclusions may be drawn : 



1. With the conditions under which the treatments were ma,de, 

 the use of one part of copper sulphate in 12,000,000 parts of water 

 is quite adequate for the elimination of Spirogyra, Cydotella, and 

 most of the Cyanophyceae. It will practically eliminate Melosira 

 and the four protozoa here listed ; for the other forms mentioned it 

 will bring about great reduction, but may not eliminate them. 



2. The use of one part of copper sulphate in 10,000,000 parts 

 of water is effective in practically eliminating all forms mentioned 

 in the list, wath the possible exception of Eudorina and Pandorina. 

 and with the conditions under which the treatments were made, this 

 amount is entirely adequate for their suppression. 



