t 



■( 



\ OF PLANTS. S85 



Germany and Italy the complete magnificence of their double 

 ^structure, and then pass again to their simple form. But it 

 is also true, that want of fertility in the soil is another fre- 

 quent cause of malformations, as we observe distinctly in the 

 Stunting and Speckled structure of the stem and branches. 



411. 



In the stem and in the branches, we observe sometimes the 

 speckled structure, sometimes the witch knots, and sometimes 

 the downward direction of the branches, as consequences of 

 malformation. What we call the Speckled structure, is an ad- 

 mired form of the wood, in which the knots are more nume- 

 rous and more mixed with each other than is usual, and a 

 great quantity of buds seem to have been but half formed. 

 Many woods, as the Birch, Poplar, and Yew wood, have a 

 particular disposition to become speckled, especially when 

 they grow on dry, stony or rocky soils. Even art can aid in 

 the production of this structure, by a frequent withdraw- 

 ing of the branches from the light ; (Marten's Theorie uber 

 die Entstehung des Masernholzes.) Connected with these 

 spots, are the witch-knots of the Scots, which are chiefly 

 found upon the Highland birches. They consist of buds in- 

 termingled in a great variety of ways, from which, however, no 

 proper branches proceed, but a crowd of thin twigs, in the 

 form of a bush or shrub, shoot out, as we often find in the 

 Pines of the very dry sandy plains of Germany ; (Keith, ii. 

 278 ; Hopkirk, p. 62.) 



From a similar cause proceeds the downward direction of 

 the branches of the Birch and Ash, which must be consider- 

 ed as a malformation, because, by propagation, it finally dis- 

 appears. 



The stem of herbaceous plants is often fascicular, or has 

 that structure which is called Fasciation. In Asparagus, 

 Hieracium cerinthoides, Carduus palustris, Celosia cristata, 

 and Ranunculus bulboms, this structure is observed to be 

 more or less permanent, in so much, that in the case of Celch- 

 sia^ it remains almost unchanged, provided the mode of treat- 

 ment be entirely the same. This fascicular form seems to 

 arise from th^ union of a number of branches, as may be dis- 



