System of the Female ‘ Flowers' of Coniferae. 547 
The importance of this concentric structure of the bundles 
in the outer integument (seminiferous scale) of the mega- 
sporangium of Coniferae, as also of the mesarch structure 
of the bundles in their cotyledons and foliage-leaves (which 
I regard as a half-way stage from concentric towards endarch 
structure), lies in the fact of its pointing to the primitive stock 
of Fern-like plants, organisms to which this concentric or stelic 
structure of the vascular tissues is peculiar, as the source and: 
origin of the great order of Coniferae, just as it is now all but 
universally admitted to be, of the allied order, Cycadaceae, 
EXPLANATION OF FIGURES IN PLATE XXVII. 
Illustrating Mr. Worsdell’s paper on the ‘flowers ’ of Coniferae. 
The followirig are the abbreviations used in the lettering of the figures: — hit 
integument; nc., nucellus ; b. b., bundles of bract; b. s. s., bundles of seminiferous 
scale; s', si, seminiferous scale; x., xylem ; ph., phloem; px., protoxylem ; x\, 
centripetal xylem; x 2 ., centrifugal xylem; s., sclereide ; b. o., bundle of the 
ovule ; b., bract ; o. int ., outer integument ; ov., ovule ; ax., axis. 
Figs. 1-5. Araucaria Cookii. Successive stages in the orientation and branching 
of the bundle-system from the central cylinder of the axis outward to 'the appendage. 
Diagrammatic. 
Fig. 6. Araucaria Cookii . Diagrammatic transverse section of the appendage 
at the level of the sporangiurii, showing the two distinct bundle-systems of the 
bract and the seminiferous scale. 
Fig. 7. Araucaria Bidwillii. Transverse section of a concentric bundle of the 
seminiferous scale, x 220. 
Fig. 8. Araucaria Bidwillii . Transverse section of a bundle in the free ligule- 
like portion of the seminiferous scale, x 285. 
Fig. 9. Pinus sylvestris. The four bundles leaving the central cylinder of the 
axis. Diagrammatic. 
Fig. 10. Pinus sylvestris. The four bundles entering the appendage. Diagram- 
matic. 
Fig. 11. Pinus excelsa. Transverse section of a bundle in the expanded laminar 
portion of the seminiferous scale, x 220. 
Fig. 12. Microcachrys tetragona. Radial section of the appendage of the cone, 
showing the insertion of the sporangium and the bundle -system, x 35. 
O O 
