RADIATING AND CONCENTRIC ARRANGEMENTS 



43 



PLATE XXVI 



Fig. 1. 



PLATE XXIV (continued) 

 Reveal radiating and concentric arrangement of parts. 



The concentric rings, as in trees, 



Fig. 3. — Scales of fishes (after Giinther). 

 represent layers of gi-owtli. 



A. a, Centre of system ; b, concentric rings ; J, e,f, radiating portions of scale. 



B and C. Similar arrangements and similar letters as in A. 



D, E, F. Slightly modified scales, the radiating or stellate urrnngement prevailing. The arrangements seen at A, B, and C resemble 

 those occurring in transverse section of trees (Plate xxii., Figs. 1 and 2) ; certain fnngi (Plate .\xii., Fig. 3) ; crj'stals (Plate xxv., Fig. 1) ; 

 flowers (Plate xxv., Fig. 3) ; corals (Plate xxv.. Figs. 5 and 6) ; sea anemones (Plate xxvii., Fig. 4) ; limpet and scallop shells (Plate 

 xxvii., Figs. 1 and 2) ; vertical section of human brain (Plate xxvii., Fig. 3), &c. 



PLATE XXV 



Plate xxv. illustrates radiating and concentric arrangements in crystals, flowers, polypes, &c. 



Fig. 1.— Snow crystals as figured by Scoresby. These reveal wonderful symmetry and beauty of form. They display fundamental 

 radiating and concentric arrangements, and may be regarded as starting-points in organisation. Curiously enough, the divergency or 

 radiating portions of the crystals are six in number, and liexagonal forms are not uncommon in igneous rocks (Plate xl.. Figs. 1 and 

 2). Hexagonal shapes occur in the vessels and other parts of plants, in the epidermis and pigment cells of the choroid coat of the eye 

 and in the comb of the honey bee (Plate iv., Figs. 4 and 13), &c. 



Fig. 2. — Comatula or feather star (after Dallas). In its young state it is furnished with a stem, and greatly resembles a plant. 

 Shows radiating arrangement to perfection. 



Fig. 3. — Symmetrical flowers (after J. H. Balfour), showing radiating and concentric arrangements. 

 A. LoAirus nohilis. B. Ruta graveolens. 



Fig. 4. — Polype (Evdeiidrium ramosum), magnified (after Dallas). Much resembles a plant. Shows radiating and concentric 

 arrangements. Compare with Figs. 3, 5, 6 and 8 of this Plate. 



