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JOURNAL OF TIIR ROYAL HORTICULTURAL SOCIETY. 



base of tho cotyledon (tig. 114, a) f but to a point a few millimetres 

 beyond and below the seed. In slight degree, therefore, the coty- 

 ledon co-operates in the sinking of the young plant into the soil, 

 a common enough phenomenon amongst Monocotyledons. The 

 radicle now elongates, and the plumule unfolds a iirst green leaf. 

 The root soon enters on the contractile phase, and the stem, ever 

 becoming more bulky, is carried a little further down. Root 

 after root now arises from the base of tho stem, and at six 

 months the condition shown in fig. Il l, /», prevails. Tho two 

 youngest roots are in the contractile phase and exhibit the usual 

 transverse wrinkles. Two others, including the primary root 

 (on the left), are arched owing to their points of insertion having 

 been depressed by younger roots subsequent to the period of their 

 own contraction. In tig. 114, c, the year-old plant is shown. The 

 bulb is already bulky and deeply sunk in the ground owing to 

 the continuous production of fresh contractile roots from the 

 base of the stem. 



The depth at which adult plants usually occur is from 

 ir> to :>0 centimetres, ami Rimbach has shown that when this 

 depth is attained the roots then formed are less markedly con- 

 tractile than during the earlier stages. If, however, a fully 

 grown bulb be placed near to the surface, the fact is recognised 

 by the plant, and strong, contractile roots are again produced. 

 The precise nature of this remarkable form of irritability is 

 obscure ami probably complex. It is not proposed to discuss the 

 question hero, bet it sutlice to say that numerous experiments 

 carried out by Kimbach on this plant have established the fact 

 that at all stages of development a bulb of Pined ramissa 

 chlorarra is capable of producing either highly or only slightly 

 contractile roots, and that the sort formed at any given time is 

 determined by the depth in the soil at which the bulb rests. 



Tho type of Phedranassd, in which all the roots are con- 

 tractile, is widely prevalent in the orders Liliacwe and 

 Amarvllidacea\ Lilium- MattagOHi Allium iirsitium, Scilla 

 hif\ >.'m, ami / t-:ny}um rerun, ti may be quoted as examples. 



From amongst dicotyledons l-'>\i i,trui resea and Hieraeiuni 

 Pilosclln may be named as examples of the above type. 



(2) Roots not all contractile. As in type (1) tho primary 

 root does not persist. 



Arum maculdtum. — Starting as in the last type with tho 



