mall chromosome.

36. Equatorial plate of spermatogonium, 21 large chromosomes, 1 small
one.

37. First spermatocyte, synizesis stage.

38-40. First spermatocyte, synapsis stage.

41-43. First spermatocyte, bouquet stage after synapsis.

44-45. First spermatocyte, spireme stage showing the unequal pair of
heterochromosomes.

46. First spermatocyte, prophase.

47-49. First spermatocyte, metaphase.

50-51. First spermatocyte, equatorial plates, _x_ the heterochromosome
pair.

52. First spermatocyte, showing metakinesis of the unequal pair.

53. First spermatocyte, anaphase.

54-55. Second spermatocyte, equatorial plates.

56. Second spermatocyte, anaphase.

_Odontota dorsalis_ (_Family Chrysomelidae_).

57. Equatorial plate of male somatic cell from walls of the testis, 15
large chromosomes, 1 small one.

58-59. Equatorial plates of spermatogonia, 15 large chromosomes, 1 small
one.

60. Resting nucleus of spermatogonium, showing plasmosome (_p_).

61. First spermatocyte, synizesis stage.

62. First spermatocyte, synapsis stage.

63-64. First spermatocyte, spireme stage, showing the larger and smaller
heterochromosome associated with a plasmosome.

65-68. First spermatocyte, prophases.

[Illustration: STEVENS PLATE IX.

N. M. S. del.

COLEOPTERA]

PLATE X.

_Odontota dorsalis._

FIGS. 69-70. First spermatocyte, metaphase.

71. First spermatocyte, equatorial plate.

72. First spermatocyte, metaphase, showing metakinesis of the
heterochromosomes.

73-74. First spermatocyte, anaphase.

75-76. Second spermatocyte, equatorial plates.

77. Second spermatocyte, showing metakinesis of the small chromosome
(_s_).

78. Second spermatocyte, prophase, showing chromosomes longitudinally
split.

79-80. Young spermatids, _n_ the chromatin nucleolus.

81-87. A series of stages in the development of the sperm head, showing
the various phases in the history of the chromatin nucleolus (_n_).

88. Cross-sections of nearly mature sperm heads.

89-90. Equatorial plates of spermatogonia of abnormal individual, 15
large chromosomes, 2 small ones.

91. First spermatocyte from same testis, spireme stage, showing 2 small
chromosomes associated with 1 large one and a plasmosome.

92. First spermatocyte from the same testis, metaphase showing a similar
heterochromosome group.

93. Second spermatocyte from same testis, equatorial plate, showing 2
small chromosomes.

_Epilachna borealis_ (