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natural one; and the teacher will find it very interesting and stimulating 

 to compare the growth and change in the tadpoles at the schoolhouse 

 with those in the natural pond. 



As growth depends on the supply of food and the suitability of the 

 environment, it is easy to judge how nearly the artificial pond equals 

 the natural pond for raising tadpoles. It will be worth while to take 

 a tadpole from the natural pond occasionally and put it in with those 

 at the schoolhouse so that the difference may be more strikingly 

 shown. There is some danger in making a mistake here, however, 

 for there may be three or four kinds of tadpoles in the natural pond. 

 Those of the toad are almost jet black, while the others are more or 

 less brownish. If one selects only the very black ones they will 

 probably be toad tadpoles. 



Every week or oftener, a little of the mud and perhaps a small stone 

 covered with the growth of microscopic plants, and some water should 

 be taken from the pond to the artificial pond. The water will supply 

 the place of that which has evaporated, and the mud and the stone 

 will carry a new supply of food. 



The growth and changes in form should be looked for every day. 

 Then it is very interesting to see what the tadpoles do, how they eat, 

 and any signs of breathing. 



All the changes from an egg to a little toad (see the plate) are 

 passed through in about two months, so that by the first of June the 

 tadpoles will be found to have made great progress. The progress 

 will be not only in size, but in form and action. 



One of these actions should be watched with especial care, for it 

 means a great deal. At first the little tadpoles remain under water all 

 the time, and do not seem to know or care that there is a great world 

 above the water. But as they grow larger and larger, they rush up to 

 the surface once in awhile and then dive down again as if their lives 

 depended on it. The older they grow the oftener do they come to the 

 surface. What is the meaning of this ? Probably most cf the pupils 

 can guess correctly; but it took scientific men a long time to find out 

 just why this was done. The real reason is that the tadpole is getting 

 lungs, and getting ready to breathe the free air above the water when 

 it turns into a toad and lives on the land. At first the little tadpoles 

 breathe the air dissolved in the water just as a fish does. This makes 

 it plain why an artificial pond should have a broad surface exposed to 



