THE THEOEY OF WATEEING 211 



But how often is this experience disregarded. In the cold- 

 houses in which Erica, JSpacris, Hhododendron, Azalea, Acacia, 

 Melaleuca, and other Australian and Cape plants are placed, 

 you may see the careful gardener watering every day those plants 

 which show the slightest sign of dryness on the surface. 

 The consequences very soon show themselves. The stems of 

 the Ericaceae begin to rot, Leguminosse and Myrtaceae lose 

 their leaves, and other plants lose their flower-buds. Decay 

 of the roots sets in in all cases. 



The disregard of the resting period makes itself felt n 

 other ways too. Many growers believe that by increasing the 

 temperature and moisture they can awaken any resting organ, 

 and by trying to do so they often come to grief in the case of 

 tuberous plants. If the tubers of Caladia, Oyclamen, Begonia, 

 Gloxinia, &c., are placed in a hot frame for forcing, are perhaps 

 covered up with soil and kept permanently damp, it is not ger- 

 mination but decay that will set in. It is generally the mould 

 {Botrytis caTia) which causes the destruction of the tubers. 

 In some cases they can be saved by cutting out the rotten 

 portion, covering the cut with powdered charcoal, and placing 

 the tubers on the surface of the soil, where they will have 

 more light and more air. 



It must be remembered that, with few exceptions, the 

 transformation of starch into soluble sugar can only proceed 

 slowly in the storage tissues. It is also only possible to 

 gradually induce this change, and in the first instance it takes 

 place in bulbs and tubers without much water. This we may 

 readily conclude from the fact that such succulent organs 

 begin to sprout at the proper time, even when they are not 

 buried in the ground and receive no liquid water. 



The calling of a dormant organ into life or activity must take 

 place gradually, and during the first development the supply of 

 water must be but small. 



Lastly, there are still some symptoms to be mentioned which 

 should warn gardeners to be careful in the watering of their 

 plants. They make their appearance when a damp atmos- 

 phere accompanies a wet soil. For though a damp atmosphere 

 is useful and necessary at the time of active assimilation, it 

 can be very detrimental when it is excessive during the period 



