Marvels of the Universe 1083 
Respiration is carried on now by taking in water at the mouth, passing it over the concealed 
gills and expelling it at the single gill-hole at the left side of the head. Lungs, too, are beginning 
to form, and the tadpole frequently visits the surface to exercise its new power. As development 
proceeds the gills tend to fall into disuse and the lungs begin to predominate ; so that when the 
creature leaves the water as a Frog the gills will have disappeared altogether. 
This we may regard as the first true tadpole stage, for the creature now remains much the same 
shape for most of its aquatic life. By this time the part of the pond in which the spawn was laid 
is a seething mass of wriggling black ; and it will be obvious to all that it was never Nature’s inten- 
tion that all these tadpoles should reach maturity. They are the scavengers of the pond, feeding 
on anything vegetable or animal, bruising and sucking the food with their horny mouths, but 
preferring those things that have already been softened by decay. 
These tadpoles also constitute the staple food of the carnivorous creatures which share their 
haunts, such as fishes, newts and the numerous tribe of predaceous water insects. Consequently 
their ranks are sadly thinned by the time they assume the proper form of the Frog, and leave the 
water. Until now our tadpole was quite black, but with the loss of the external gills its colour begins 
to change. Its body becomes closely dotted with minute golden spots, which, as time goes on, 
SAT 7 2 
Photos by] (WwW. B. Johnson. 
TADPOLES 
The early stages of Tadpole-life are here shown of the natural size. The single Tadpole to the left has recently hatched, 
and the gills are just noticeable behind the head. The central four are a little older, and the four to the right still older. The 
tail has lengthened, the gills become feathery-looking, and the Tadpoles swim freely. 
gradually expand, and give the creature the familiar brown colour, This admirably protects it 
from unwelcome observation, while lying at the bottom of a muddy pond. Tadpoles are always 
active and feeding. Their mission is to feed, and on the refuse which would decay and poison 
the water were it not removed by them. Naturally our tadpole grows rapidly, and after a few 
weeks from the date of hatching the hind toes become visible at the root of the tail. At the same 
time within the gill chambers the front legs begin to develop, although they are as yet invisible 
from the outside. 
Steadily these legs lengthen and grow stouter, and by the middle of June the hind pair become 
folded in the position so characteristic of a Frog. 
Then the left fore-leg suddenly pushes its way out through the gill-hole, but the right one has 
to forcibly make an exit in the skin and, in consequence, appears some hours later. The little 
creature now is a veritable Frog, but with a tadpole’s tail. This, however, is not for long, for as 
soon as it is the proud possessor of four legs the tail begins to wither. A sort of inflammation sets 
in at the tip and gradually the tail shortens to a stump, and in three or four days is absorbed and so 
vanishes altogether. 
The little Frog now wanders into the grass at the waterside and in time reaches the meadows, 
feeding on the tiny insects it meets with, A summer shower will cause the simultaneous exit of 
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