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DE. M. T. MASTERS ON THE MORPHOLOGY, 



















Araucaria CooJcii presents an illustration of trimorphic foliage, 

 the primordial leaves immediately following the cotyledons are 

 concrescent, widely spreading and linear ; those on the main 

 stem or leader-shoots are oblong acute, and much longer than 

 those on the side branches, which are ovate, acute, densely 

 packed, and appressed. 



In the ordinary form of Cryptomeria japonic a the concrescence 

 of the base of the leaf is very marked ; but there are varieties in 

 cultivation analogous to the so-called Eetinosporas, in which the 

 foliage over the whole tree is of a different character to that of 

 the type, as in ft elegans, ft Lobbii, and ft. torta of gardens. 

 The cones of ft elegans, a form analogous to Betinospora squar- 

 rosa, do not materially differ from those of the type, nor does 

 the anatomical construction of the leaf (apart from difference 

 in the shape) differ from that of the normal type. 



The internal structure of the two forms of leaves is, indeed, 

 practically the same, except that the stomata are usually much 

 more abundant on the spreading than on the appressed leaves. 

 The stomata often occupy a relatively large triangular area at the 

 base of the spreading leaves. This circumstance leads to the 

 conjecture that one purpose of the presence of these spreading 

 leaves is to secure a freer access of light and a fuller elimination of 

 gases through the stomata, and that they may in some way act, as 

 in facilitating the storage of nutritive matter of which the quickly 

 growing extension shoots may avail themselves (see antt, p. 249). 





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Relation of \Proto7norpJ1ic Leaves to Congenital or to 



External Conditions. 



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The appearance of these protomorphic or primordial leaves in 

 the adult condition and their persistence in Eetinosporas can 

 only be attributed to an arrest of development, or to the absolute 

 non-occurrence of developmental changes. It is interesting to 

 correlate these forms of leaves with the relatively slow growth of 

 the branches and the disposition of the stomata, the different 

 position and grouping of which as compared to that in the 

 ordinary leaves, points to some functional diversity. 



The relation between the primordial and less highly specialized 

 leaves and those which characterized their progenitors is an 

 interesting subject for enquiry, but one upon which as yet little 

 but conjecture can be hazarded. 



The superficial resemblance of the primordial leaves to those 



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