











278 



DH. M. T. MASTERS OS THE MORPHOLOGY, 





nature of the needle of this plant may be classed under three 

 heads, according to which the needle is (a) foliar or conjointly 



) 



true 



In spite of the peculiar position of the liberian and of the 

 vascular elements of the bundle, Von Mohl* considered the 

 needles as leaves and compared them to the seed-scales of the 

 Abietineae, in which the same relative position of the elements 

 occurs. Mold's explanation is that the needle consists not of 

 one, but of two leaves belonging to an abortive shoot axillary to 

 the primordial leaf as the seed-scale of the cone of Abietinese is 

 to the bract. He accounted for the peculiar position of the xylem 

 and phloem by supposing that the union of the two leaves took 

 place by the margins directed towards and adjacent to the main 

 axis, so that the under surface, and consequently the phloem, 

 came to be directed towards the axis and the upper, or xylem, 

 surface in the opposite direction. 



This may be represented by the annexed diagrams : 











■ 



© 



© 



Fig. 12 



© 



L 



Fig. 13, 



For explanation, see text. 



wherein the circles marked 1 represent the main axis, those 

 marked 2 the secondary axis, with the mother leaf L below and 

 the two secondary leaves Z, Z, one on each side of the secondary 

 axis. In fig. 12 the lateral leaves Z, Z are represented in their 

 natural position, and the xylem x also. In fig. 13 the secondary 



Z, I are indicated iu union by their posterior 





lateral 



leaves 



■ 



. 



- 





















■ 



* 







* 



• 









- 

 - . 





. 



* Mohl in Botan. Zeitung (1871), p. 101. 















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1 

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