60 The dwellers in the soil 



show very few specks and are little altered. These 

 creatures making the specks came from the soil because 

 so few are found on the jelly alone ; they were killed 

 in the baking and so do not occur on the baked soil 



jelly. 



You can also show that breathing is going on in the 

 soil even after you have picked out every living thing 

 that you can see. First of all you must do a little 

 experiment with your own breathing so that you may 

 know how to start. Shake up a little fresh lime with 

 water and leave it to stand for 24 hours. Pour a little 

 of the clear liquid into a flask or bottle fitted with a 

 cork and two tubes, one long and one short like that 

 shown in Fig. 27. Then breathe in through the tube A 

 so that the air you take in comes through the lime 

 water: notice that no change occurs. Next breathe 

 out through the tube B so that your breath passes 

 through the lime water ; this time the lime water turns 

 very milky. You therefore alter in some way the air 

 that you breathe: you know also that you need 

 fresh air. 



Now we can get on with our soil experiments. Take 

 two small flasks of equal size fitted with corks and 

 joined by a glass tube bent like a U with the ends 

 curled over. Put some lime water into each flask and a 

 little water in the U-tube. Now make a small muslin 

 bag like a sausage : fill it with moist fresh garden soil, 

 tie it up with a silk thread and hang it in one of the 

 flasks by holding the end of the thread outside and 

 pushing in the cork till it is held firmly (see Fig. 28). 

 Fix on the other flask, and- after about five minutes 

 mark the level of the liquid with a piece of stamp 

 paper; leave in a warm place but out of the sun. 



