EXPLANATION OF THE FIGURES. 455 



PLATE XIV. 



KIELLA REUTERI. Mont. 

 FIG. 



1 and 2. Germ-plants with spore attached, x 150. 



3. A plant produced by the multiplication of a cell of a leaf separated mecha- 



nically from an older individual, x 130. 



4. Adventitious shoot of an older plant, X 150. 



5. Full-grown shoots (cultivated, more slender than in the natural state) ; 



the older part of the plant is dead, X 5. 



6. Another similar shoot, x 20. 



7". The end of the shoot a of the latter, x 200. 



8. Terminal bud of a strong shoot after the removal of the older leaves, 



X 200. The leaves and the upper layer of cells of the massive portion 

 of the stem which latter, as far as the drawing extends, consists of only 

 two layers of cells are shown in dark lines above the outlines of the 

 membranous wing and the second cellular layer of the stem. 



9. Longitudinal section of a terminal bud perpendicular to the surface of the 



stem, x 200. 



10. Terminal bud after the removal of all leaves. Two antheridia are being 

 formed, the one sunk half down, the other deep down into the duplica- 

 tions of the margin of the wing, x 150. 



10. Young unicellular antheridium with adjoining tissue, laid bare by a sec- 

 tion parallel to the surface of the wing of the stem, x 150. 



12. Longitudinal section of a half-ripe antheridium, x 150. 



13. Section through a portion of a fertile shoot which has laid bare an arche- 



gonium recently impregnated, and has grazed a lateral axis bearing 

 antheridia, X 100. 



14 a . Unimpregnated archegonium with its apex still closed, X 250. 

 14*. Archegonium ready for impregnation, X 250. 



15. Longitudinal section of a recently impregnated archegonium, x 250. 



16. Young calyptra just visible through its veil, X 25. 



17. Longitudinal section of a calyptra with sporangium (a younger state than 



Fig. 16), x 200. 



18. Longitudinal section of the same when half ripe, the section not having 



passed through the mouth, x 100. 



19. Mother-cell with four spores enclosed in special-mother-cells, x 250. 

 19*. Rudimentary elater from the same sporangium, x 250. 



PLATE XV. 



Figs. 1 18. Marchantia polymorpha. 



1. Longitudinal section perpendicular to the surface of a shoot bearing a very 



young bud-receptacle, x 50. 



1*. The bud-receptacle of the last figure cut through, x 200. 



2. Young bud, x 400. 



