MINUTE STRUCTURE OP PLANT HYBRIDS. 285 



Plate IV. 



Fig. 1. Upper leaf epidermis of Dianthus alpinus, x 120°. 



Fig. 2. Upper leaf epidermis of Dianthus Grievei, x 120°. 



Fig. 3. Upper leaf epidermis of Dianthus barbatus, x 120°. 



Fig. 4. Lower leaf epidermis of Dianthus alpinus, x 120°. 



Fig. 5. Lower leaf epidermis of Dianthus Grievei, x 120°. 



Fig. 6. Lower leaf epidermis of Dianthus barbatus, x 1 20°. 



Fig. 7. Transverse section, stem of Dianthus alpinus, x 85°. e., epidermis ; eo., cortex ; c, cork ; i.e., inner 



cortex; ph., phloem; ca., cambium; x., xylem. 

 Fig. 8. Transverse section, stem of Dianthus Grievei, x 85°. Letters as above, s., sclerencbyma, absent in last. 

 Fig. 9. Transverse section, stem of Dianthus barbatus, x 85°. Letters as above. 



Fig. 10. Surface view of leaf epidermis from Dianthus alpinus, stained in watery eosin, x 450°. I., leucoplast. 

 Fig. 11. Surface view of leaf epidermis from Dianthus Grievei, x 450°. 

 Fig. 1 2. Surface view of leaf epidermis from Dianthus barbatus, x 450°. 

 Figs. 13a, 136, 13c. Petals of Dianthus alpinus, D. Grievei, and D. barbatus; nat. size. 

 Figs. 14a, 146, 14c. Outlines of nectar glands from above plants, exposed in longitudinal section. 



Plate V. 



Figs, la, 16, lc. Transverse sections, roots of Geum rivale, G. intermedium, and G. urbanwm, showing cork 



layers formed during successive years. 

 Fig. 2. Maturing achene of Geum rivale, x 8°. The style-arm (s.a.) projects as a rounded knob (s.a.k.) at its 



attachment to the tip of the style (s.). 

 Fig. 3. Maturing achene of Geum intermedium, x 8°. The style-arm (s.a.) has a slightly projecting knob, as 



has also the style at the point of attachment of the two. 

 Fig. 4. Maturing achene of Geum urbanum, x 8°. The style (s.) projects as a rounded knob (s.k.) at its attach- 

 ment to the style-arm (s.a.), which is devoid of any projection. 

 Figs. 5a, 56, 5c. Petals of above three plants ; nat. size. 

 Figs. 6a, 66, 6c. Pollen grains of above three plants, x 400°. Two small bad grains are shown from the 



hybrid (66), though these compared with the good grains are greatly in the minority. A bad one 



from Geum rivale is seen in fig. 6a. 

 Fig. 7. Transverse section, stem of Ribes Grossularia, x 75°. e., epidermis; eo., outer cortex; c, cork; i.e., 



inner cortex; ph., phloem; x., xylem. 

 Fig. 8. Transverse section, stem of Ribes Culverwellii, x 75°. Letters as above. The specimen figured was 



from a thick twig, and the cork development has been excessive. 

 Fig. 9. Transverse section, stem of Ribes nigrum, x 75°. 

 Figs. 10a, 106, 10c. Pollen grains of above three plants, x 350°. 

 Figs. 11, 12, 13. Surface views of under leaf epidermis of above plants. Fig. 11 x 150° ; Fig. 12 x 150° ; Fig. 



13 x 200°. 



Plate VI. 



Figs. 1, 2, 3. Leaves of Saxifraga Geum, S. Andrewsii, and S. Aizoon, clarified to show disposition of vascular 

 bundles to water stomata ; nat. size. 



Figs. 4, 5, 6. Surface views of water stomata and surrounding tissue from above three plants, x 450°. Saxi- 

 fraga Geum is devoid of circumstomatic knobs, the hybrid has sixteen of these in the figure, and 

 8. Aizoon has thirty. 



Figs. 7a, 76, 7c. Petals of above three plants, slightly enlarged from nat. size. 



Figs. 8, 9, 10. Longitudinal sections of flowers of Saxifraga Geum, S. Andrewsii, and S. Aizoon, x 50°. 

 s., sepals. These sepals are strongly reflexed in fig. 8, form an angle of 120° with continuation of 

 the main axis in fig. 9, and an angle of 30°-35° in fig. 10. 



