1906] YAMANOUCHI—POLYSIPHONIA VIOLACEA 443 
43- Mitotic figure in the old region of thallus, showing large centrosphere- 
lke st. pace. 
1G. 44. Polar view of the same stage as the above, showing 20 chromosomes. 
Mitosis in the vegetative cells of the tetrasporic plant. 
Figs. 45-51. All apical cells of main filament. 
Fic. 45. Resting nucleus, showing linin network. 
Fic. 46. Chromatin granules commence to aggregate to form prochromo- 
somes, 
Fic. 47. Early prophase showing 40 chromosomes. 
Fic. 48. Metaphase showing equatorial plate; centrosphere-like structures 
Ftc. 49. Late metaphase; groups of daughter Solan separated. 
Fic. 50. Polar view of metaphase showing 40 chromosom 
Fic. 51. Anaphase; vacuole intruding between two Sia of daughter 
chromosomes. 
PLATE XXIi, 
Spermatogenesis. 
Figs. 52-61. Formation of the sperm mother cell. 
Fic 52. Terminal portion of a very young antheridium, consisting of an axial 
siphon of three cells; the nucleus of the lower cell is in a resting condition; the 
middle one in early prophase; and the upper one in anaphase. 
Fic. 53. Mitotic figure in a cell of the axial siphon to form a stalk cell laterally. 
Fic. 54. A cell of the axial siphon with the stalk cell formed laterally. 
Fic. 55. Prophase in the stalk cell showing 20 chromosomes. 
Fic. 56. Metaphase showing equatorial plate; centrosphere-like structures 
Fic. 57. Polar view of the same stage as in the preceding figure, showing 20 
chromosomes. 
Fic. 58. Late metaphase stage; nuclear membrane still present. 
FR 9. Anaphase; vacuole intruding between two groups of daughter 
en cen 
Fig. 60. Still later stage of anaphase. 
IG, sh ee cleavage furrow separating the sperm mother cell from 
the stalk 
Figs. 62-74. Formation of the first sperm. 
Fic. 62. Resting nucleus of sperm mother cell, showing linin network. 
Fic. 63. Fine reticulum transformed into 20 prochromosomes. 
Fic. 63a. Portion of fig. 63 under higher magnification. 
Fic. 64. Prophase; a few spindle fibers attached to the chromosomes; centro- 
Some-like bodies at the poles. 
Fic. 64a. Portion of fig. 64 under higher magnification 
Fic. 65. Metaphase; the centrosphere-like structures evident. 
