EXPLANATION OF THE FIGURES. 449 



FIG. 



22 4 . A portion of the uppermost bud of the former figure, x 600. The dotted 

 lines show the course of the two nuclei during the molecular motion 

 which they exhibited. 



23. Two spore-mother- cells held together by the common membrane of the 



mother-cell, after the formation of the tertiary nuclei, X 300. 



24. A similar mother-cell somewhat more developed, X 300. 



Figs. 25 37 6 . Fossomlrotiia pitsilla. 



25. Two-celled rudiment of a leaf, X 300. 



26. A young leaf with eleven cells, x 300. 



27. 28. Tips of somewhat more developed leaves, x 300. 



29, 30. Sections of young archegonia, fig. 29, x 100 ; fig. 30, x 400. 



31. Section of au archegonium in whose central cell the germinal vesicle is 



being formed, x 300. 



32. Section of an archegonium in whose central cell the germinal vesicle is 



completely formed, and the primary nucleus almost dissolved, X 300. 



33. Longitudinal section of an archegonium, with its central cell almost filled 



by the germinal vesicle, X 300. 



34. Spore-mother-cell, after the formation of the four tertiary nuclei, X 300. 



35. Mother-cell from the same capsule, after long soaking in water. The inner 



layer of the cell-membrane is much swollen, and has squeezed the con- 

 fluent cell-contents into a globular lump, x 300. 



36. Young elater from the same capsule after soaking in water for a short time. 



The middle layer of the cell-membrane is thuch swollen, and has ruptured 

 the outermost one. x 300. 



37. Longitudinal section of a ripe autheridium whose apex has burst by the 



separation of the cells and the tearing of the cuticle, x 150. 



37*. Ruptured mother-cellule of a spermatozoon, which is escaping out of the 

 fissure, x 600. 



PLATE VII. 



Figs. 1 3. Haplomitrium Hookeri. 



. Longitudinal section of the apex of a leafless subterranean shoot, x 300. 



2. Similar section of a similar shoot farther from the apex, X 300. 



3. Similar section of a detached young fruit rudiment, x 300. 



4. Trichocolea tomentella. Longitudinal section of a terminal bud, X 200. 



5. Madotheca platyphylla. Longitudinal section of an autheridium, x 200. 



6. Ripe mother-cell of a spermatozoon from the same. 



Figs. 79. Ptilidlum Ciliare. 



7. Half of a young leaf, x 150. 



8. A young leaf slightly more developed, detached from the stem and ex- 



panded, x 200. 



9. Lateral view of a terminal bud, which has developed a lateral branch close 



underneath the apex. 



29 



i 



