ELONGATION. 433 



speaking, the appearances presented in such cases are 

 not sufficiently striking to demand notice other than 

 as regards their size. One illustration, however, may 

 be cited from its singularity. This was the case of a 

 dahlia, in which the centre of the flower was occupied 

 by a projecting knob as large as a walnut, bro'svn in 

 colour, and very hard in texture. This knob was 

 nothing but the enlarged and indurated extremity 

 of the common receptacle, destitute of the scales and 

 florets which usually spring from it. No insect-puncture 

 could be detected, and no other reason for this peculiarity 

 could be ascertained. 



CHAPTER II. 



ELONGATION. 



The class of cases coming under this head are 

 sufficiently indicated by the name. There are many 

 instances of this phenomenon occurring under different 

 conditions, which, though unusual, can hardly be called 

 abnormal, such, for instance, as the great lengthening 

 of roots in their search for water, the excessive elon- 

 gation that takes place in plants when -grown at a 

 distance from the light, in their endeavour to attain to 

 which they become, as gardeners phrase it, " drawn." 

 A similar result is brought about in forests or planta- 

 tions, where long spars are required, by allowing the 

 trees to grow very close to each other, so as to prevent 

 the lateral extension of the branches. When plants 

 grow in running water their roots, stems, and some- 

 times their leaves, become excessively elongated, as in 

 Banuncuhts fluitans, the flower-stalks of Valisnerla 

 spiralis, &c. These are cases of variation rather than 

 of malformation, but are none the less curious, or 

 sometimes perplexing; thus, Lapeyrouse described, in 



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