38 
FIRST BOOK. 
young ones on milk^ and that ihej are covered 
with horny scales or plates. They have cold 
blood ; and, as they breathe by lungs and not by 
gills, they are air-breathers." 
TADPOLES AND FROGS. 
1. Look here, Harry/' said Mr. Green to his 
little boy, as he pointed to something, almost like 
a lump of jelly^ which he had just drawn from 
the pond. What 
is this?" 
Harry could not 
tell. 
2. " It is a cluster 
of eggs," said his 
father. In each 
of the round, clear 
eggs you may see 
a black speck ; that 
is the yolk, and 
the sticky, jelly- 
like covering is 
something like the ' white ' of a bird's egg. " 
3. " But those eggs have no shells," said Harry. 
" That is true, but still they are really eggs, as 
you shall find out. I shall not tell you what 
Frog's Eggs. 
