An introduction to the study of cytology / by L. Doncaster.

Leonard Doncaster

Date:: 1920

Credit: An introduction to the study of cytology / by L. Doncaster. Source: Wellcome Collection.

16/352 page 10

$CHAP. VII. The Cytoplasmic Structures in Spermato- genesis and Oogenesis .... The spermatozoon—Its development—Mitochondria— The acrosome and Golgi apparatus—Oligopyrene and apyrene spermatozoa—Accessory cells—The egg— Yolk and nutritive cells—Egg membranes. \ III. Fertilisation and Segmentation . . . hi Entrance of spermatozoon—Fertilisation membrane and prevention of polyspermy—Conjugation of nuclei —Segmentation—Position of cleavage planes—Centro- lecithal segmentation—Polyspermy. IX. Parthenogenesis ...... 125 Parthenogenetic eggs with one polar division—Fer- tilisation by second polar nucleus—Parthenogenetic eggs with two polar divisions—Hymenoptera— Phasmidae—Gall-flies—False fertilisation—Summary. X. Artificial Parthenogenesis .... 140 Methods — Theoretical explanations — Comparison with fertilisation—Chromosomes and centrosomes— Artificial parthenogenesis in frogs—Sex. XI. The Cytological Basis of Sex-Determination 152 Hymenoptera: haploid and diploid chromosome series —Heterochromosomes—Idiochromosomes—Life-cycle of Aphids and Phylloxerans—Hermaphroditism: Rhab- donema—Lepidoptera. XII. Gf.rm-cell Determinants .... 172 Germ-plasm and germ-track—Germ-cells of A scans— Of Sagitta—Miastor—Pole-plasm in other Insects— Oosoma of Litomastix—Ectosomes of Copepoda— Oocyte of Dytiscus—Sertoli cells—Nature of germ-cell determinants. XIII. The Theory of the Individuality of the Chromosomes ....•• *88 The hypothesis of individuality—Evidence from abnormal numbers—Persistence of chromosomes in the resting nucleus—Differences of size and shape— Hybrids—Differences of function of chromosomes— Microsomes as units. PAGE 91$

An introduction to the study of cytology / by L. Doncaster.

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