•244 Brown : Algal periodicity 



Spirogyra varians is the most widely distributed alga found in 

 this region. It grows under varied conditions. It conjugates at 

 all seasons of the year, depending on hard external conditions, 

 e. g., the drying up of a pond. 



i water slightly stagnant at a tem- 



surface-watei at a 



It 



ChaetopJiora thrives best in water 

 perature from 5 C. to 25 ° C. 



Draparnaldia plnmosa thrives in 

 temperature from i° to 15 C. 



Cladophora glomerata grows best ii 

 persists throughout the year in the locality studied but is in a 

 growing condition only a few weeks in the spring, while there is a 

 brisk flow of moderately pure water. 



Spirogyra nitida is the most abundant of the Conjugatae in 

 the small stagnant ponds about Bloomington. 



A CLASSIFIED LIST OF THE ALGAE FOUND, TOGETHER WITH 

 BRIEF DATA ON THE FORMS NOT DISCUSSED ABOVE 



CHLOROPHYCEAE 



Conjugatae 



Zygnemaceae 



Spirogyra Link 



nitida (Dillw.) Link 



crass a Kiitz. 



varians (Hass.) Kiitz. 



neglecta (Hass.) Kiitz. Bayou along lower 



part of stream no. 1, 1 1 Je to I Au '07. 

 Weberi Kiitz. 

 inflata (Vauch.) Rabenh. 

 rkndaris Rabenh. Water-works reservoir, 29 



Je '07. 

 Zygnema Kiitz. 



insigne Kiitz. 



leiospcrmnm De Bary 

 cruciatitm Ag. 

 Moitgcotia De Bary 



genuflexa (Dillw.) Ag. (Platrocarpus mirabdis 



A. Br.) 

 sca/aris Hass. 

 parvida Hass. 



