LIST OF FIGURES 



lo. 

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PAGE 



Epidermis of larval salamander 2 



Amceba Proteus 4 



Cleavage of the ovum in Toxopneustes 8 



Diagram of inheritance 11 



Diagram of a cell 14 



Spermatogonium of salamander 15 



Group of cells, showing cytoplasm, nu- 

 cleus, and centrosome 16 



Alveolar or foam-structure of proto- 

 plasm, according to Biitschli 18 



Living cells of salamander, showing 



fibrillar structure 20 



Nuclei from the crypts of Lieberkiihn. 24 



Special forms of nuclei 25 



Diffused nucleus in Trackelocerca. ... 26 



Ciliated cells 30 



Nephridial cell of Clepsine 32 



Nerve-cell of frog 33 



Diagram of dividing cell 35 



Diagrams of cell-polarity 39 



Remak's scheme of cell-division 46 



Diagram of the prophases of mitosis. . 48 



Diagram of later phases of mitosis. ... 50 



Prophases in salamander cells 54 



Metaphase and anaphases in salaman- 

 der cells 55 



Telophases in salamander cells 56 



Middle phases of mitosis in Ascaris- 



eggs 58 



Mitosis in pollen-mother-cells of lily. . 59 



Heterotypical mitosis 60 



Mitosis in Infusoria 62 



Mitosis in Euglypha 63 



Mitosis in Euglena 64 



Mitosis in Noctiluca 65 



Mitosis in Actiiiosphcsrium 66 



Pathological mitoses in cancer-cells.. . 68 



Pathological mitosis caused by poisons 69 



Mechanism of mitosis in Ascaris 71 



Leucocytes 72 



Pigment-cells 73 



Mitosis in the egg of Toxopneustes. ... 76 



Nuclei in the spireme-stage 78 



Early division of chromatin in Ascaris 79 



Amitotic division 81 



Volvox 89 



Ovum of Toxopneustes gi 



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PAGE 



Ovum of Nereis 95 



Insect-egg 96 



Micropyle in Argonauta 97 



Germ-cells of / 'olvox 98 



Diagram of the flagellate spermatozoon 99 

 Spermatozoa of fishes and amphibia. . 100 

 Spermatozoa of birds and other ani- 

 mals 102 



Spermatozoa of mammals 104 



Unusual forms of spermatozoa 105 



Spermatozoids of Ckara 106 



Spermatozoids of various plants 107 



Germ-cells of Hydractinia 109 



Primordial germ-cells of Ascaris, no 



Primordial germ-cells of Cyclops 112 



Egg and nurse-cell in Opkryotrocha . . . 114 



Ovarian eggs of insects 115 



Young ovarian eggs of various animals 116 

 Young ovarian eggs of birds and mam- 

 mals iiS 



Young ovarian eggs of earthworm. . . 120 



Formation of the spermatozoon 124 



Transformation of the spermatids of 



the salamander 125 



Fertilization of Physa 131 



Fertilization of Ascaris 133 



Germ-nuclei of nematodes 134 



Fertilization of the mouse 136 



Fertilization of Pterotrachea 137 



Entrance and rotation of sperm-head 



in Toxopneustes 138 



Conjugation of the germ-nuclei in Tox- 

 opneustes 139 



Fertilization of Nereis 141 



Fertilization of Cyclops 142 



Continuity of centrosomes in 'Ihalas- 



seina 144 



Entrance of spermatozoon into the egg 146 



Pathological polyspermy 147 



Polar rings of Clepsine 150 



Paths of the germ-nuclei in Toxo- 



pneustes 152 



Fertilization of Myzostonia 158 



Fertilization of Pilularia 160 



Fertilization of the lily 161 



Diagram of conjugation in Infusori.i. . 164 



Conjugation of Paramaccium 166 



