34 NATURE TEACHING 



ment with germinating barley. The best method of 

 fastening the seedlings is to pass an ordinary pin through 

 the two cotyledons, taking care not to injure the young 

 stem or root (see Fig. 2). 



Examine after twenty- four hours, comparing the 

 marks on the root with those on the card. 



It should be found that the first one or two divisions, 

 near the tip, have not altered in length ; that the next 

 ones have grown a great deal ; while those still further 

 back have remained stationary like those at the tip. 

 Make a drawing of a root as first set up, with the marks 

 at equal distances, and after one, two, and three days, 

 showing exactly the position of the marks at each of 

 these times. 



From this simple experiment we learn that in a 

 root the greatest amount of growth is not at the 

 apex, but some little way behind it, so that the root- 

 tip protected by its root-cap is, as it were, driven 

 down through the soil by the rapid growth of the 

 portion just behind it. 



Absorption by Roots. 



Take two small bottles having short, narrow necks, 

 and fill both with water. To one add a few drops of 

 eosin solution or a little red ink, just enough in either 

 case to colour the .water distinctly red. To the second 

 bottle add a little carmine which has been previously 

 rubbed to a thin paste with water. Take two seedlings, 

 such as those previously examined for root-hairs (p. 30), 

 and fix one in each bottle so that its roots are immersed 

 in the liquid. This may be done by wedging them 



