490 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



metres across may arise between the two cut surfaces. Three 

 stages in the sinking of a young plant of Plmdranassa chloracea 

 into the soil from this cause are illustrated in fig. 114. 



The contractility of roots is effective in this way not only 



g. 114.— Three Stages in the Establishment of Young Plant or 

 1 Ph.edranassa chloracea' in the Soil : (a) Seedling with cotyledon 

 in seed and one leaf raised above the surface. (b) Six-month-old " 

 plant with four contractile roots, two of which, now arched, are no 

 longer effective, (c) Year-old plant sunk still deeper. The dotted line 

 represents the surface. (After Rimbach.) 



with vertically placed stem-structures, but also in many cases of 

 horizontal rhizomes, runners, and the like (e.g. jirum macula- 

 turn, Ii-is ge7inanica,F rag aria vesca), though of course in many 



