THE TALE OF THE TADPOLES 



The spheres of jelly buoy up the eggs and at the 

 same time prevent overcrowding. In the little 

 chinks between the spheres there are often groups of 

 microscopic green plants which liberate oxygen in 

 the sunlight and use up the carbonic acid gas which 

 the developing eggs produce a profitable associa- 

 tion, a miniature illustration of the Balance of 

 Nature. But there is a fauna as well as a flora of 

 frog-spawn, and the chinks are tenanted by small 

 fry such as water-fleas and rotifers some of which 

 eventually loosen the gelatinous envelopes, helping 

 the larval-frogs to escape. Others, it must be 

 admitted, seem to wait to devour. And again, the 

 envelopes of jelly are useful in lessening the risks of 

 jostling which might be fatal to the delicate em- 

 bryos when the wind raises waves in the pond, or 

 when a water-hen or coot splashes in among the 

 spawn. Moreover, the jelly seems to be unpalatable 

 to most water animals, and it is so slippery that few 

 birds can make anything of it. Finally, it may be 

 that the clear spheres serve as so many greenhouses, 

 helping the ova to make the most of the sun's rays. 



The Hatching 



About a fortnight or three weeks after the eggs 

 were laid and fertilized, the minute larvae are hatched 

 from the delicate envelope of the ovum, and begin 

 to wriggle about in the dissolving jelly. They are 

 somewhat awkward-looking, half-made creatures at 

 first, and when they get clear of the jelly they are 

 mouthless, limbless, eyeless, and gill-less. They 

 attach themselves, often in long rows, to water- weed, 



19 



