EXPLANATION OF THE FIGURES. 459 



PIG. 



7. An unusually small pro-embryo ; on the left, near the lower angle, the bud 



of a leafy shoot is seen. A new pro-embryo has originated at one of 

 the rows of cells springing from the marginal cells. X 100. 



8. Basal fragment of a highly developed pro-embryo to which the spore is still 



attached. The smaller longitudinal moiety of the leafy bud, which is 

 seated very near the cell, has been removed by the section. X 200. 



9. Lobe of a pro -embryo, without any processes from the marginal cells, with 



a bud attached, x 100. 

 11, ]2. 11 a very young, 12 a half ripe autheridium, in longitudinal section, 

 X 300. 



13. Ripe spermatozoa, killed by iodine, x 800. 



Figs. 14 17. Sphagnum cymbifolium. 



14, 15. 14 a very young archegonium, 15 archegonium near the period of 



opening; in longitudinal section, X 250. 



16, 17. Longitudinal sections of the ends of stems in which the rudimentary cells 

 of a lateral branch have been exposed by the section (see the left side of 

 both figures ; in fig. 16 underneath the uppermost, in fig. 17 under- 

 neath the second uppermost leaf). X 150. 



18. Schistostega osmundacca. Portion of a pro-embryo, X 300. 



PLATE XIX. 



Pigs. 1 16. Funaria hygrometrica. 



14. Sections of antheridia in different stages of development, x 300. 

 5 8. Mouths of unimpregnated archegonia. 6 and 7 the central cell, 

 X 300. Figures 5 and 6 are young states, figures 7 and 8 more de- 

 veloped conditions. 

 9. Young fruit-rudiment in longitudinal section, X 300. 



10. The upper end of the same, X 300. 



11. Upper part of a growing calyptra, with the upper half of the enclosed fruit- 



rudiment : in longitudinal section. The fruit-rudiment which has not 

 been cut through is shown in an optical longitudinal section. X 300. 

 11*. The fruit-rudiment out of the same calyptra, detached, turned round 90, 

 and in longitudinal section, X 300. 



13. Spore-mother-cell after the formation of the two secondary nuclei, X 400. 



14. The same; after the formation of the four tertiary neuclei, X 400. 



15. The same; after the divisions of its internal cavity into four special mother- 



cells, X 400. 



16. The same ; after considerable thickening of the walls of the special-mother- 



cells and the formation of the spore-membrane, x 400. 



17. Longitudinal section of the upper half of the mouth of a recently impreg- 



nated archegonium of Dicrannm Jieteromalhcm. Underneath is the primary 

 cell of the fruit-rudiment detached from the central cell of the arche- 

 gonium by contact with the dissecting needle. X 300. 



18. Bryum cocspiticium. Rudiment of a lateral bud, detached and seen ob- 



liquely from above, x 300. 



