Marvels of the Universe 1081 
same water is chosen year after year, and, too, the same part of the pond ; while other pieces of water, 
seemingly just as suitable, are invariably ignored. 
The female Frog deposits her eggs in the water in the form of a small black mass, not more than 
an inch and a half in its longest dimension. If this were laid out of water it would feel to the touch 
much the same as tacky rubber solution ; and the mass on close inspection would be seen to consist 
of a quantity of tiny jet-black spheres, all tightly pressed together. The tackiness is due to a 
minute coating of a sort of gelatine on each sphere. Now, when laid in water, as is the case in nature, 
this gelatine-like substance, which entirely envelops each egg, rapidly absorbs water and becomes 
Photo bu] cw. R. Johnson. 
FROG’S EGGS HATCHING. 
Many of the spherical envelopes have burst and released the small tadpoles. 
a slippery jelly. In a few hours this original black mass swells up to a lump of jelly, in which are 
embedded at regular intervals the tiny black bodies already mentioned. These are the actual 
eggs, the jelly being merely a protective covering. 
Our first illustration is a mass of frog-spawn at this stage and the black eggs will be seen, each 
in its own covering of jelly. This gelatine covering plays a very important part in the subsequent 
welfare of the eggs. They require a constant supply of the oxygen dissolved in the water, and 
as the jelly is very porous it keeps the eggs apart and allows the water free access. However, even 
in nature, the innermost eggs seldom hatch out of a big mass, on account of their being blanketed 
by the more fortunate ones on the outside. 
Anyone who attempts to pick up a quantity of frog-spawn will readily see how ably the slippery 
jelly foils the attacks of birds and fishes, which would gladly prey on the black eggs were they not 
