1082 Marvels of the Universe 
thus prevented. The spawn is always laid in some shallow where it cannot sink more than half 
an inch or so below the surface ; for the eggs require light and heat from the sun to hatch them ; 
and their black colour largely aids in this absorption. 
In some ten days or more after they were deposited the eggs show signs of changing shape. No 
longer are they practically spheres, for these black bodies appear to unroll. Reference here to 
the illustrations will make this perfectly clear. As the embryo tadpoles develop, the jelly 
gradually loses its toughness, as it were, and becomes slimy and mucilaginous, so that when the 
young tadpole is ready to leave the spawn it is able to slowly wriggle its way through the jelly 
out into the water. It is a curious little creature now, jet black and just a head, body and 
stumpy tail, but without a suggestion of limbs. Under its head is a gland which secretes an 
adhesive substance that causes the tadpole to stick to anything the gland touches. In this way 
the creature fastens itself to the outside of the mass of jelly or to the weeds amongst which the 
spawn was deposited. Gradually it works its way upwards until the spawn is covered on top with 
these young tadpoles. ; 
They have no mouths yet, and are incapable of any movement beyond an occasional wriggle 
They breathe by means of tiny gills which, at this stage, somewhat resemble ears at the side of 
the head. In a few days the tail lengthens and the gills grow to be feathery-looking appendages, 
and then the creatures begin to swim freely. Gradually these new gills disappear, for a skin grows 
over them until they are no longer visible and a horny, beak-like mouth is formed. 
S 
Photo by] ; 
cw. B. Johnson. 
FROG’S EGGS HATCHING. 
In this photo, though some of the eggs in the lower part of the mass have not yet hatched, the free tadpoles are wriggling 
their way to the top to enjoy the greater light and warmth of the surface waters. 
