OF ORNAMENTAL TREES. 35 



ripened wood, are planted in light or sandy 

 soil, and plunged in material a few degrees 

 warmer than the atmosphere. Over the cut- 

 tings bell-glasses are placed. These are the 

 main points variations being made to suit 

 peculiarities of each kind. Now for the 

 principles. Half-ripened wood contains the 

 " descending sap," out of which roots are 

 formed. Cuttings are " too young" when 

 the sap has not been elaborated ; " too hard" 

 when the descending current is feeble, or has 

 ceased. The sandy soil admits air, which is 

 essential to the formation of roots. Bottom 

 heat excites the base of the cutting, encour- 

 aging it to form roots before the top starts 

 into active life. Bell-glasses prevent evapo- 

 ration from the leaves and stems, checking 

 their demand for nutriment till the roots are 

 formed to supply them. Let us carry this 

 illustration to our subject. 



21. In planting, the immediate object is to 

 get a speedy formation of new roots or fibres. 

 The best time to plant, then, will be when 

 the earth is a few degrees warmer than the 

 atmosphere, and when the elaborated sap is 



