90 NATURE TEACHING 



Examine these same leaves with a lens, looking care- 

 fully for the very small pores. As the above experiment 

 has shown, these are often present only on the lower sur- 

 face of the leaf. 



Take a tumbler, fill it half-full of water coloured with 

 a little red ink or eosin. Place some leafy shoots 

 (balsams or lime twigs do admirably) with the cut ends 

 of their stems dipping in the water, and leave them for a 

 day in a light place in a warm room. The stems become 

 marked with red lines, and finally the leaves also. This 

 coloration is due to the water which passes up the 

 bundles of the stem and their continuation in the leaves 

 (the veins), and, being red, colours them, thus indicating 

 the path in the stem along which water travels. 



Note the manner in which the leaves of many grasses 

 roll up during very dry weather. This may also be 

 observed by bringing the grasses into the room and 

 noting the change as the leaves become dry. Observe 

 the positions assumed by the leaves of other plants 

 during dry weather, or at the middle of the day when 

 the sun is very hot, noting whether they roll up or droop. 

 The leaves of house-leeks, laurel, holly, and other thick- 

 leaved plants do not roll up. They are sufficiently pro- 

 tected by their thick skin. 



Observe during rain, or while watering with a water- 

 ing-can with a very fine rose, the direction in which the 

 water is conducted by the leaves of the plants growing 

 in the garden. Compare this with the distribution of 

 the roots, and particularly of the young rootlets by which 

 water is absorbed. Note the course of the water and 

 the arrangement and character of the roots, in beet-' 



