LIFE HISTORY OF THE TOAD 93 
single summer, but the tadpoles of bullfrogs and green frogs 
require two seasons to complete their development. These 
latter tadpoles hibernate in the mud with adult frogs and 
toads. 
79. Life History of the Toad. — In many respects the 
toad’s life history is similar to that of the frog. The eggs 
Figure 79. —Tadpoles. 
The smallest tadpole, black, on the bottom of the aquarium jar is a toad 
tadpole about three months old. The other two tadpoles on the bottom are 
frog tadpoles about three months old; while the two tadpoles with legs are 
frogs. The larger is about one year old and the smaller three months old. 
This marked difference in size and growth is natural as each kind takes a 
different length of time to go through metamorphosis. 
of the toad are laid in stagnant water in strings of a jellylike 
substance. (Figure 80.) The eggs hatch in from five to ten 
days into wriggling tadpoles, which feed on the microscopic 
plants that are found in water. They swim by means of 
their tails. Respiration is accomplished by means of the 
outside gills which allow the oxygen from the water to reach 
the blood and the carbon dioxide to enter the water. Later 
the inside gills take over the work of the outside gills and the 
