Vol. 35 







BULLETIN 



No 5 



OF THE 



TORREY BOTANICAL CLUB 



MAY, 1908 



Algal periodicity in certain ponds and streams 



Harry B. Brown 



It is a matter of common observation that algal growths may 

 suddenly appear in ponds and streams, persist for a short time, 

 then disappear with equal suddenness. Doubtless many have 

 noticed this in a casual way and wondered why the plant appeared 

 so suddenly, or why it disappeared. In order to answer these 

 questions, or to form even a good opinion of the causes underlying 

 this irregularity, one must study the algal growth in a certain pond 

 or stream at frequent intervals throughout a year or more, noting 

 the different species of algae present, their relative abundance, time 

 of fruiting, etc., and all the external conditions under which the 

 plants are growing at any particular time. These conditions will 

 include amount of light, depth and extent of the body of water, 

 rate of flow and change of water, temperature, amount of mineral 

 matter in the water, cormophytic growth, animal life in the water, 

 and any effect man may have had, as in draining ponds, emptying 

 rubbish, or sewage, etc., into the water. 



But little careful and systematic study has been devoted to this 

 subject. Fritsch * ('06) has given the subject some study. In 

 his paper he makes some good suggestions in regard to methods 

 and gives some interesting observations based on a somewhat ir- 

 regular study. 



During April, 1906, the writer began the study of the algae in 

 a small stream flowing across the campus of Indiana Univer- 



* 



Slt y, and in two ponds near Bloomington. This observation ex- 

 tended throughout April, May, and June, 1906. The following 



* Fritsch, F. E. Problems in aquatic biology with special reference to the study of 

 a] gal periodicity. The New Phytologist 5 : 150-169. Jl 1906. 



[ The Bulletin for April, 1908 (35 : 155-222. //. 6-/0) was issued 29 Ap 1908.] 



223 



