66 



Fresh-water Biology 



EQUIPMENT 



For the work outlined in the following pages certain equipment is desirable: 



1. Personal equipment. 



(a) Clothing suitable for field work. 



(b) Note book, soft pencil for labelling, hard pencil for drawing and red and green 



pencils for diagrams. 



(c) A pocket lens. 



(d) Containers, suitable for brining materials collected back to the laboratory in 



fit condition for study. Quart glass jars for living materials, and vials of alcohol 



for ''pickles" are recommended. 



These things the student should take and care for in the field. 



2 . Equipment for common use. 



That part of it needed for each study should be provided by the instructor, delivered 

 at the place where needed for use, and returned to storage afterward. The 

 numbers in parentheses after the items in this list indicate the pieces required 

 for a field class of twenty students: Pans (10), lifters (20) and pails (2), dip nets 

 (10) and sieve nets (3), seines (1), hand screens (5), and weed rings (2), plancton 

 nets (1) and thermometers (1). 



A recently devised net for general collecting, one that will serve for more uses than 

 any other known to us, is the apron net shown in figure 7. It is so shaped at the front that 

 it may be pushed through water weeds or under bottom trash. Its wide-meshed cover al- 

 lows the animals to enter while keeping out the weeds and coarser trash. A final push 

 through the water lands the catch at the rear, where it is easily accessible for picking-over 

 by hand. 



The smaller animals that are mixed with the trash in the net may best be found by 

 dumping the contents of the net into a white dish, where they will at once reveal their 

 presence by their activity. They may be taken from the water most easily and without 

 injury on a lifter such as is shown in figure 3. 



This net may also be used for scraping up and sifting the bottom mud and sand to ob- 

 tain burrowers. It may be used for collecting the insects and other animals that abound 

 among the loose stones in rapid streams 

 by setting it edgewise against the bottom 

 facing upstream and stirring the stones 

 above it. The animals, dislodged by the 



stirring, will be swept by the current into ^^^^1^ ■" ^ . ^, \JX\^ i ^ 



the net. 



Old leaf drifts, caught on obstruc- 

 tions in the current, may be stirred in the 

 same way to get the animals hiding in 



them; but more stirring and overturning Fig. 7. The Apron Net. 



of the leaves will be necessary to dislodge them. 



