and hypoderm of i layer ; 2 ducts, lateral in mesophyll ; Palisade on upper surface 

 (2 rows), no plication, spongy mesophyll with intercellular spaces : central stele 

 circular (350 fx diam.), 2 distinct V.B. ; fibres central and over phloem; transfusion- 

 tracheides few and scattered laterally. 



A. pectinala closely similar, but less specialized in details (shade-leaves): 1 in. 

 long, 1 mm. wide ; spongy mesophyll more definitely plicated ; 2 ducts on lower 

 surface, peripheral. 



V. Pseudotsuga Douglasii : needles of Abies-type, 30 mm. long and \\ wide ; 

 grooved on upper surface ; hypoderm in patches ; palisade on upper surface ; central 

 mesophyll with slight plication ; 2 ducts peripheral on lower hypoderm : 2 stomatal 

 tracts on lower surface (6 cut in each in section): guard-cells sunk 15 [x : Central 

 stele, 250^,, distinct endodermis ; 2 V.B. closely confluent, scl. fibres, transfusion- 

 tracheides, and alb. cells as clearly defined groups. 



VI. Tsuga canadensis: needles 12 mm. long and 2 broad, ot Abies-type, 

 grooved on upper surface, 2 stomatal tracts on lower. No sclerosed hypod., epidermis 

 with very thick outer walls, guard-cells and subsidiary-cells conspicuously lignified ; 

 one median duct below phloem ; palisade on upper surface (2 rows) ; no plication : 

 stele small, with no distinct endodermis; 2 V.B. closely applied; few transfusion- 

 tracheides scattered, and alb. cells. 



C. Comparison of leaves of other Conifers. 



I. Sequoia gigantea: acicular type (4 mm.), section rhomboidal, 1-3 mm. 

 wide ; epidermis and hypoderm thick walled and sclerosed, stomata on both sides ; 

 V.B. one central only, with few scl. fibres on both sides. One median duct over 

 phloem; endodermis not marked; transfusion-tracheides as remarkably extended 

 wings to V.B., with bordered pits ; albumen-cells few. 



II. Sciadopitys verticillata : 'Double-needle,' 2-pointed, 4 in. long, and 

 3 mm. broad ; deep median furrow, with stomatal tracts, on theoretically upper 

 surface. Stomata with solid papillose subsidiary cells (45 fx), thick-walled lignified 

 guard-cells ; sclerosed hypoderm, mesophyll as palisade, 1-2 layers, and loose spongy 

 tissue ; 2 V.B. (of theoretical units) widely spaced : endodermis ill-defined ; pitted 

 transfusion-tracheides as wing-extensions of xylem convergent on upper side : re- 

 markable branched sclerites; resin-ducts (10) peripheral ; xylems give the upper side. 



III. Juniperus communis, acicular needle, 10 mm., upper surface flat, with 

 one broad stomatal tract (marked by wax-lines) ; epidermis and thick-walled 

 hypoderm ; palisade chiefly on lower surface : one larger central V.B., and one 

 median duct on lower side ; a few scl. fibres over phloem. Transfusion-tracheides 

 as pronounced wing-extensions with reticulated thickening. 



IV. Cupressus Lawsoniana, phyllomorphic branches with adpressed foliage 

 scales, dorsal and ventral flattened (1 mm.), flanking members rhomboidal in section 

 (^ mm.) ; sclerosed epidermis and hypoderm ; palisade ; median V.B. cut obliquely : 

 guard-cells lignified on inner sides of leaves in protected chinks. Large resin -cyst 

 in axial part only; no endodermis; transfusion-tracheides on flanks of xylem, 

 considerably developed in D and V members. 



V. Araucaria imbrieata; Hard leaf, not a 'needle'; row of V.B. across 

 centre, alternating with resin-ducts : Hypoderm of isolated scl. strands ; no plicate 

 mesophyll ; stomata on both sides, guard-cells sunk 30 fx ; palisade on both sides ; 

 sclerites large and massive with calc. oxalate crystals in wall ; transfusion-tracheides 

 as convergent wings of V.B., relatively more developed in smaller bundles, of cells 

 with bordered pits. 



VI. Araucaria excelsa, acicular type, rhomboidal in section, to 2 mm. diam., 

 or laterally compressed : stomata on all sides; central series of 5 1 V.B. (one being 

 median) as reduction-limit of a D.V. lamina, not a ' needle ' : Ducts between the 

 bundles and others peripheral, in the limit one median : Sclerites with Ca. ox. rhombs ; 

 transfusiori-tracheides often more than the normal xylem. 



VII. Agathis australis; lamina with D.V. construction, palisade on upper 

 surface and stomata only on lower. Epidermis aqueous, with outer wall 10 /x thick; 

 hypoderm of tannin-cells and scl. fibres scattered, more on upper surface, and over x 

 and <. V.B. in median series, small ; resin-ducts alternating ; transfusion-tracheides 

 inconspicuous, lateral. Stomata sunk 20 fx in cup of subsidiary cells, guard-cells 

 sclerosed. 



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