THE GROWTH OF THE SHOOT FROM THE BUD 53 



It is because a plant is constantly giving out water that it is 

 necessary to water it regularly. Young gardeners generally give 

 too much water. It is important not to over- water, especially in 

 frosty weather, but in warm weather, when evaporation is going 

 on rapidly, water is necessary. As a rule, it is best not to 

 water unless sufficient water can be given; surface watering 

 does more harm than good. Too much water rots the roots, 

 for this reason it is bad to leave pot plants standing in water 

 day after day. 



(iii.) RESPIRATION. Although all the parts of a plant respire, 

 the leaves are specially concerned in this work. Air enters 

 through the thin cuticle when the leaf is young, through the 

 stomata when the cuticle gets thicker, and carbon dioxide is got 

 rid of by the same channels. 



Through their manifold work of carbon assimilation, trans- 

 spiration, and respiration, leaves profoundly affect the atmosphere 

 around them. All visitors to the seaside know what a difference 

 trees make to their enjoyment of the place ; it is the drawback of 

 some of our resorts that one is exposed to the glare cf a pitiless 

 sun without the shade of the green foliage so restful to the eye. 

 Leaves prevent that dryness of the atmosphere which may become 

 unpleasant, from the fact that water is being given out by them. 

 Trees, too, attract clouds laden with moisture, and thus may be 

 the means of securing moisture in a dry region ; it is a well-known 

 fact that the cutting down of forests, or even the thinning of trees 

 in a garden, will make a difference to the degree of dampness of 

 a house. Leaves also help to purify the atmosphere, for they 

 need the carbon dioxide which is being constantly breathed out 

 by all living things. When it is remembered that in this country 

 our parks, meadows, pastures are carpeted with millions of blades 

 of grass all using carbon dioxide under the influence of sunlight, 

 and that the leaves of all our herbs, shrubs, and trees are also doing 

 the same thing, it is hardly possible to overestimate the beneficial 

 work done by leaves in keeping the atmosphere fit to breathe. 

 Not only are they using the carbon dioxide of the air, but they 

 are returning to the atmosphere the oxygen which has been 

 separated from the carbon. 



