88 



PRINCIPLES OF PLANT-TERATOLOGY. 



number, even an infinity of growth-centres involved or 

 latent within the orp'an, which continuously and sue- 

 cessively assert themselves as the organ increases in 

 age, so that, as in the case of a fasciated wall-flower 

 shoot observed, the ultimate branches produced are 

 very numerous and finely subdivided, eventually be- 

 coming resolved into foliage-leaves pure and simple 

 (PL VI, fig. 1).* Further, owing to the fact that 

 in almost all " fasciations " some growth-centres are 

 weaker than others, giving rise to branches which, while 

 equal in grade or value to the others, are smaller 

 in diameter and less rapidly elongating, the curious 

 phenomenon of winding of the shoot is produced, 

 which is an almost invariable concomitant of fasciation. 

 It is the same phenomenon as is seen in the twining of 

 climbing plants, its essential characteristic consisting 

 in the bending of the axis out of the vertical direction 

 at every turn (PI. VI, fig. 1). This may, in some cases, 

 become so pronounced that the axis becomes com- 

 pletely inverted (PI. VII, fig. 1). This winding of 

 the axis must not be confused with the phenomenon 

 of torsion or twisting, which is a totally different one 

 in which the axis never leaves the vertical direction of 

 growth. It will be referred to later. 



If we suppose the normal single "growth-centre" to 

 be replaced by (i. e. to become segmented into) two 

 only, and these two to be equally balanced as regards 

 strength and development, the branching to which they 

 give rise would be an approach to dichotomy, f as 

 defined in the text-books. 



2. Trigonal Fasciation. — There may be further 

 mentioned those cases where the transverse extension 

 of growth is not in one, but in two dimensions. 

 Peduncles of the cowslip (Primula veris) were observed 

 so strongly developed as to represent a three-fold 

 organ ; in transverse section the organ would appear 

 three-lobed, and if branching could have occurred 



* Cf. the " phy ton-theory. 



f Nestler regarded the tip of a fasciated shoot as composed of a continuous 

 row of apical cells ( f Vegetationslinie')- 



