INTRODUCTION. xliii 



winter come on, constant moisture at the roots, added to 

 the natural humidity of the atmosphere, is very injurious 

 to them. In the frigid regions they inhabit, the approach 

 of winter brings rapid and constant congelation of the 

 moisture both of the earth and the atmosphere, and 

 the plants are immediately brought to rest, and remain, 

 for a period always longer than the duration of our win- 

 ter, in a state of dormancy almost as complete in its 

 arrestment of functional activity as death itself This 

 completeness of rest can never be secured to them in 

 cultivation ; but the nearer we attain to it the greater 

 will be the success. The drainage of the rockwork, 

 whether natural or artificial, is therefore of the first 

 importance ; and the best means devisable in the cir- 

 cumstances should be adopted to cut off or control the 

 percolation of moisture in natural rock during winter, 

 when in nearly every case it is liable to increase rather 

 than diminish. For if abundantly supplied with mois- 

 ture, these plants, peculiarly sensitive as they are to 

 every alternation of temperature, will now be tortured 

 into abortive and exhausting attempts at growth, and 

 again suddenly become ice-bound, many times in our 

 comparatively short but variable winter. In choosing a 

 site for an artificial rockwork, low, humid, shady situa- 

 tions should, for the reasons just stated, be avoided. A 

 free airy position is the best, and it should, of course, be 

 harmonious with the surroundings — natural, not artificial, 

 features ought to prevail around it ; and the design or 

 fashion of it, and the extent, should be regulated by 

 sound views as to what is natural and tasteful — fanciful- 

 ness being easily detected and always objectionable in 

 such matters — and by the idea of breadth which the scene 



