THE FARM STREAM 43 
the rapids. Note the 
extent of mud, sand, 
gravel, rubble, and flat- 
stone bottom, and their 
relation to slope and cur- 
rent. Note also the 
physical conditions that 
organisms have to meet 
a 5 ‘ Fic. 24. The larvae of four two-winged 
in each situation. flies (Diptera): a, the swale-fly (Sepedon), 
F withdrawing beneath the surface film of the 
Collect and examine water; b, the punkie (Ceratopogon); c, the 
phantom midge larva (Corethra); and d, the 
the commoner plants common midge (Chironomus). 
and animals, first of the 
rapids and then of the still water, omitting the fishes, 
(except to note where they are seen.) 
The Record of this study will consist of: 
I. A map, on which are indicated as clearly as possible: 
Waterfalls and riffles. 
The extent of each sort of bottom. 
The principal plant beds. 
The fish pools. 
RW DN 
II. List of all the water plants observed, arranged in a 
table with column headings as follows: 
Name (this will be supplied by the instructor). 
Grows where (thatis, in which of the situations examined). 
Depth of water (approximate). 
Growth-habit (simple or branched, erect or trailing, stem- 
less, leafless, etc.). 
Remarks. 
III. List of all the water animals observed, arranged in a 
table with column headings as follows: 
Name (this will be supplied by instructor, if needed). 
Lives where (in which of the situations examined). 
