Yasni. — On the Life-history of Salvinia natans. 481 
Fig. 5. Cross-section of the same stage as above, x 600. 
Fig. 6. The third wall-cell (w 3 ) is just formed ; the archesporium is now surrounded by three 
wall-cells, x 600. 
Fig. 7 * a > cross-section of a young microsporangium in which the second wall-cell is divided 
into two ; b , the upper surface view of the same, x 600. 
Fig. 8. The first tapetum-initial (/,) is segmented from the archesporium. x 600. 
Fig. 9. The third tapetum-initial is cut off from the archesporium ; h, the nucleus of the third 
tapetum-initial. x 600. 
Fig. 10. The second division of the central cell, x 600. 
Fig. 11. The same as above, x 600. 
Fig. 12. A later stage ; the four cells are formed, x 600. 
Fig. 13. A still later stage; the eight cells are formed. x 600. 
Fig. 14. Cross-section of a microsporangium in which sixteen spore-mother-cells are formed 
X 600. 
Fig. 15. Cross-section of a microsporangium in which the microspore-mother- cells are at the 
synapsis stage and the tapetum-cells are degenerating, x 600. 
Fig. 16. A microspore-mother-cell in the resting stage, x 1400. 
Fig. 17. The microspore-mother-cell in synapsis, x 1400. 
Fig. 18. A microspore-mother-cell in spireme stage, x 1400. 
Fig. 19. Multipolar spindle stage, x 1400. 
Fig. 20. The same as above, x 1400. 
Fig. 21. Cross-section of the equatorial plate, x 1400. 
Fig. 22. Longitudinal section of a heterotypic spindle, x 1400. 
Fig. 23. A later stage of the same, x 1400. 
Fig. 24. The same in telophase, x 1400. 
Fig. 25. A later stage ; the reconstruction of the daughter-nuclei has begun, x 1400. 
Fig. 26. Two daughter-nuclei are just formed, x 1400. 
Fig. 27. Prophase of the second division. x 1400. 
Fig. 28. A later stage of the second division, x 1400. 
Fig. 29. The telophase of the second division, x 1400. 
Fig. 30. The wall formation between four granddaughter-nuclei, x 1400. 
Fig. 31. Young microspore just formed, x 1400. 
Fig. 32. Young free microspore, x 1400. 
Fig. 33. A microsporangium containing microspore tetrads, x 600. 
Fig. 34. A later stage ; individual spores are separated from each other, x 600. 
Fig. 35. Longitudinal section of mature microsporangium, showing microspores at the periphery, 
x 600. 
Fig. 36. A mature microspore, x 1400. 
Fig. 37. A germinating microspore ; the nucleus is in division, x 1400. 
Fig. 38. The first division is completed, x 1400. 
Fig. 39. The lower of the two cells is dividing to form the root-cell below, x 1400. 
Fig. 40. A little later stage ; the upper of the two cells has already divided into two. x 1400. 
Fig. 41. The division of the apical cell, x 1400. 
Fig. 42. A later stage of the same, x 1400. 
Fig. 43. A still later stage, a.c ., apical cell ; a.m.c ., antheridium-mother-cell. x 1400. 
Fig. 44. The lower antheridium-mother-cell, being separated from the upper antheridium- 
mother-cell by a sterile cell, is differentiated, s.c., sterile cell, x 1400. 
Fig. 45. The wall-cell (w.c.) of the upper antheridium is formed, x 1400. 
Fig. 46. The wall-cell of the lower antheridium is formed; the root-cell (r.c.) is shown, 
x 1400. 
Fig. 47. The nucleus of. the central cell of the upper antheridium is just divided, while that 
of the lower antheridium is in the telophase of the division, x 1400. 
Fig. 48. A slightly later stage of the same, x 1400. 
Fig. 49. The last division in the central cell of the lower antheridium. x 1400. 
Fig. 50. A nearly mature male prothallium ; spermatozoids are developing in the sperm-cells 
of both antheridia. x 1400. 
Fig. 51. About the same stage as the preceding ; the root-cell is shown, x 1400. 
