





ANATOMY, AND LIFE-HISTORY OF THE CONIFERS. 



279 



















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margins and dragged out of position, with the result of displacing, 

 or apparently displacing, the xylem and the phloem. 



Engelmann • Strasburger f, and Van Tieghem J also consider 

 that the needle is due to the concrescence of the two leaves which 

 spring from an axillary shoot, the development of which is arrested 

 so that no trace of a, punctum vegetationis or growing-point can 

 be seen in the adult condition. It may be added that no trace 

 whatever of the supposed axillary shoot can be seen at any period 

 by microscopical examination of the buds, nor any evidence of the 



torsion and displacement of the leaves, 

 symmetry and compares 



k 





scale) 



yeloped in the axil of the bract of the cone of Abietineae. 



Celak 



( 



dopitys to be the morphological equivalent of the seed-scale of 

 AbietineaB. 



The late Prof. Dickson thought that the needles represented 

 phylloid shoots or cladodes like those of Buscus rather than 



leaves \\. 



a 



There is nothing," he says, "in the developmental 



grow 



evidence to prove that the arrested punctum vegetationis is not at 

 the apex of the organ between the two projecting points, and if 

 it be at the apex then the organ must be regarded as a cladode." 

 Dickson was confirmed in his opinion by the occasional develop- 

 ment of branches from the notch of the needle, as first observed 

 hy Carriere % the branching being due to the 

 at the apex, where it usually remains arrested. Dickson, like all 

 other observers, points out that the position of the xylem and 

 phloem is the same in the needles of Sciadopitys, the cladode of 

 Buscus, and the seed-scale of the Abietineae. Bower also de- 

 scribes the cladode of Ruscus as growing in a similar manner to 

 that described in Sciadopitys. 



Goebel adopts a similar view to that of Dickson, pointing out 













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i 









i 









* 









Engelmann in Sitzb. Ges. naturforsch. Freund. Berlin (1868), p. 14. 

 t Strasburger, Conif. und Gnetac. (1872), p. 382. 



I Van Tieghem, Traite de Botanique (1884), p. 1320. 

 § Bertrand in Ann. Sci. Nat. (1878), t. xii. p. 67. 



II Dickson, " Phylloid Shoots of Sciadopitys," Report Internat. Bot. Congress, 



I*>ndon (1866), and Journal of Botany (1866), p. 224; "Foliage-leaves of 



Hiwxis? Trans. Bot. Soc. Edinb. xvi. (1885), p. 140, t. ix.-xi. See also for 



Rttscm, Van Tieghem, in Bull. Soc. Bot. France, Feb. 22, 1884. 



1 Carriere in Gard. Chron. (ex Revue Hprticole), May 2, 1868, and March 1, 

 1884. 



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