THE FROG 161 
So soon as the eggs are laid they are abandoned, and the 
animals leave the water and resume their ordinary life on 
land, until the change of seasons again compels them to go 
into winter quarters. 
Bony Framework.—Figure 104, which shows the 
skeleton of the Frog, will indicate the build of the animal. 
Note the low depressed skull, the large orbits, the differ- 
ence in the length of the fore and hind limbs, the number 
of digits on each limb, and the absence of ribs enclosing 
the chest. | 
The Egg.—A Frog’s egg, when first laid, is a small 
spherical body covered with a thin gelatinous layer, which 
quickly swells up in the water 
into a transparent globe, in the 
centre of which a small black 
speck, the true egg, can be seen. 
The jelly surrounding the egg 
serves a two-fold purpose. It 
acts as a float, keeping the eggs 
Fig. 105.—Eges, showing small at the surface of the water, and 
a names are ii ingiobe enabling them to obtain the 
warmth necessary for their 
developmen. It is, moreover, extremely slippery and 
difficult to grasp, and so serves as a protective covering 
against the attacks of birds, fishes, and the larvee of insects. 
The Tadpole.—In a short time the spherical mass 
developes into a small black elongated creature, all head 
and tail, known as a Tadpole. On first emerging from the 
egg, the tadpole is very helpless; it has no mouth, and 
makes but a poor attempt at swimming. When in this 
condition, it attaches itself to water weeds, hanging on by 
means of suckers, with which the underside of its head is 
provided. On the sides of its neck are several pairs of fine 
hair-like outgrowths—the external gills, by means of which 
L 
