630 Wolfe . — Cytological Studies on Nemcdion . 
Fig* 3 2 - Division almost complete. A hyaline region of the protoplasm marks the position of 
the future wall. 
Fig* 33* The wall forming. 
Fig. 34. Cell-division complete. 
Spermatogenesis . 
Fig. 35. A young antheridial branch. 
Fig. 36. An antheridium being formed. The nucleus in anaphase. About eight chromosomes 
are present. 
Fig. 3 7. Antheridia in various stages. 
Fig. 38. Nuclear division in the antheridial branch. No centrosome apparent. 
Figs. 39 and 40. The centrosome is seen in some cases. 
Fig. 41. Nuclear reorganization. 
Fig. 42. The chromatophore is protruding into the antheridial mother-cell, and about to divide. 
Fig. 43. A chromatophore in the antheridium. 
Fig. 44. Granular material appears at the distal end of the antheridium. No chromatophore 
can now be differentiated. 
Fig. 45. The nucleus appearing within this material. 
Fig. 46. The nucleus is now greatly increased in size, and shows definite aggregations of 
material on the nuclear wall. The antheridium is now mature. 
Fig. 47. The antheridium after it has been discharged into the water. A median section. 
Fig. 48. The same in surface view. 
Fig. 49. An antheridium conjugating with the trichogyne, and dividing into two sperm-cells. 
Fig. 50. A similar stage. 
Mitosis. 
Fig. 51. Illustrating the structure of the nucleolus, with the chromatin at the periphery and 
surrounding a lightly staining substance. Radiating fibrillae are present. 
Fig. 52. The chromatic material gathering into clumps. 
Fig. 53. Probably centrosomes. 
Figs. 54 and 55. The chromatin is passing along fibrillae out of the nucleolus to the nuclear 
wall. Prophase. 
Fig. 56. Somewhat later. Also an extrusion of nucleolar substance. 
Fig. 57. The nucleolus at this stage is somewhat lenticular in shape. 
Fig. 58. The chromatin granules are now aggregated into morphological chromosomes. 
Fig* 59* The chromosomes are grouped in the equatorial region of the nucleus. 
Fig. 60. A similar stage. 
Figs. 61-63. The chromosomes are gathering at the nuclear plate. The spindle is now present 
with distinct centrosomes at the poles. 
Figs. 64 and 65. Metaphase in the sporophyte. About sixteen chromosomes present. 
Fig. 66. Anaphase. 
Fig. 67. The reduction division, showing about eight chromosomes. 
Fig. 68. The same stage, but showing in addition an extrusion of nucleolar material. 
Fig. 69. The anaphase of the reduction division. 
Figs. 70-72. Stages in the fusion of the chromosomes to form the daughter-nucleoli. 
Figs. 73 and 74. Vegetative prophase corresponding to 54 and 60, respectively, in the 
cystocarp. 
Fig* 75* Vegetative metaphase corresponding to 64 in the sporophyte, and to 67 of the 
reduction stages. 
