GENERAL OBSERVATIONS. 23 



individual members remain in their original close lateral contact. 

 It is impossible to exaggerate the importance of the acceptance 

 of such a generalization. At one sweep it clears away all the 

 foundations of the Schimper-Braun theory, and all other formulae 

 based on the study of mature cylindrical organs with isolated 

 members, which from the time of Bonnet have been regarded as 

 the types of construction, and for which expressions were required 

 by descriptive systematists.* 



4. Phyllotaxis of Cynara Scolymus, L. 



The great inflorescence heads of the cultivated Globe Artichoke 

 produced an involucre of protective scale leaves 8-9 inches in 

 diameter in the expanded head. These form a definite spiral series 

 starting from a very low divergence on the elongated main axis 

 and reaching a very high one at the periphery of the disk. The 

 scales are large and the insertion of the lower one quite clear, so 

 that these may be easily numbered in rotation (fig. 9), and the series 

 finished off by Braun's method. The numbering is quite definite, 

 and the system clearly presents a "rising phyllotaxis." Thus if 

 the sixth member were over the first, it would be f , but it is not ; 

 nor does 9 come opposite 1, nor again 14, though 22 is so near, that 

 taking all the leaves in sight as in Sempervivum, it might be con- 

 sidered sufficiently accurate. If the series has stopped at any one 

 of these points and remained constant afterwards, the transition 



* Henceforward, therefore, the term phyllotaxis vviU be used exclusively for 

 the primary arrangement of lateral members at the moment of their actual 

 development on the growing-apex. Schwendener, following the custom of 

 systematists, uses the term as applicable to any leaf arrangement at any part of 

 the plant, as cal ciliated, that is to say, by the very questionable method of 

 orthostichies. Thus the terminal bud of Pinus sylvestris would present scale- 

 leaves and spur-branch origins with a divergence of |^, while in the shoot 

 immediately below the divergence was /j. It is clear that the arrangement at 

 the growing-point is the feature of primary importance ; subsequent alterations 

 are secondary in character, and the actual arrangement observed in adult mem- 

 bers may present merely the obscured relics of a primary construction ; the 

 hypothesis that the phenomena observed on an adult member has been from 

 the first the aim of the organism having no satisfactory basis. 



