EXPLANATION OF THE FIGURES. 475 



PLATE XLIII. 



riLULAKIA GLOBULIFERA. 

 FIG. 



1. Longitudinal section of a ripe large spore. 



2. Longitudinal section of the upper part of a large spore at the first com- 



mencement of germination, x 300. 



3. Lateral view of a very young prothallium, X 400. 

 3*. The same cut through longitudinally, X 400. 



4. Longitudinal section of a germinating spore, with the prothallium still con- 



cealed between the lobes of the outer spore-membrane, X 50. 



5. Longitudinal section of a young prothallium, x 300. 



6. A small spore whose inner membrane has burst and from the fissures in 



which the motber-cells of spermatozoa are emerging ; from some of the 

 latter the spermatozoa are escaping, x 600. 

 6 6 , 6 C , 6 d . Spermatozoa in different positions ; 6*, one which has just made its 

 way out of the mother-cell, X 500. 



7. The upper part of a germinating inner spore seen from the outside, with 



some spermatozoa, X 150. 



8. Longitudinal section of a prothallium ready for impregnation, X 500. 



9. Prothallium ready for impregnation (or just impregnated ?) in longitudinal 



section. The contents of some of the cells of the covering layer, and also 

 the layer of a portion of the outer spore-membrane, is shown. X 400. 

 10, 11. Longitudinal sections of prothallia just impregnated, enclosing rudi- 

 ments of embryos, X 300. 



12. Prothallium with a more developed embryo, in longitudinal section, X 300. 



13. Embryo of a similar prothallium, x 300. 



14. Prothallium with an embryo which is beginning to develope the first frond, 



in longitudinal section, X 300. 



15. Embryo enclosed by the prothallium iu the act of forming the first frond and 



the first root, X 300. 



16. Longitudinal section of an abortive prothallium, X 300. 



PLATE XLIV. 

 Figs. 1 7. Pilularia globulifera. 



1. Longitudinal section of a prothallium containing an embryo about to burst 



forth, X 50. 



2. Longitudinal section of a spore and germ-plant whose first frond has 



broken through the prothallium. 

 2 6 . Bud-end of the latter germ plant, x 300. 

 2. Root-end of the latter germ-plant, x 300. 



3. Longitudinal section of a young macrosporangium, x 300. 



4. Central cell of the latter, rather more developed, x 300. 



