10 
ANIMAL ACTIVITIES. 
In this way the water siphons over into the sink. To 
prevent the passage of insects through the siphon, attach 
it to a tunnel 
having the open¬ 
ing covered with 
wire gauze. 
Hydra. Collect 
small sticks and 
dead leaves, with 
some mud and 
water, from a fresh¬ 
water pond, or from 
ditches used for 
draining swampy 
Fig. io.— Other Pondweeds. places Place 
these in glass with 
growing fresh-water plants, and renew from time to 
Fig. ii.—T he Hydra ( magnified ). 
time the water lost by evaporation. Collect from 
several localities in separate jars, and label the jars 
