14 ANIMAL ACTIVITIES. 
actual size from time to time, dating the sketches. 
Make these sketches as accurate as possible. When 
not convenient to catch tadpoles it is easy to buy 
them. 
Fishes. Obtain alive, by using a net, either horned 
pout (catfish) or bream. Goldfish can be bought in 
case of failure to get others. Feed with fish-food, a 
preparation of gelatin sold by dealers in goldfish. Use 
plants in the aquarium, and change the water about 
three times a week. Use a rectangular aquarium. 
Shield from the direct rays of the sun. 
Hydroids and Jelly-fish. Unless a school is situated 
where it is easy to obtain an abundant supply of salt 
water, not many marine animals can be well kept. 
Before undertaking seashore work, a copy of ‘‘ Seaside 
oes 
Fic. 19.—A Campanularian Hydroid Colony (Eucope diaphana). a, 
whole colony, one half natural size; 4, single zooid magnified; 
¢ and d, stages of jelly-fish, magnified. 
Studies ’’ (Agassiz) should be accessible to both teacher 
and pupils. There are many small marine animals 
resembling the hydra. Among the most abundant of 
these are the campanularian hydroids, colonies of hydra- 
like animals. The colonies are brown in color, and 
look like mosses or similar plants. They grow on 
