LIST OF FIGURES. 



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Fig. I. Formation of spermatozoa in Ascans tnegalocephala 



II. Formation of ova ,, ,, ,, 



III. Behaviour of idants during the development of germ-cells 



IV. Formation of spermatozoa in Pyrrhocoris 



V. Diagram of a double idant 



VI. Formation ,, ,, 



VII. Wreath of four idants 



VIII. Maturation of parthenogenetic egg 



IX. Germinal vesicle of parthenogenetic egg oi Artemia 



X. The two varieties of Cypris reptans, A and B. 



XI. Conjugation o{ Paramaecium ..... 



XII. Diagram of the conjugation of Co//'/V/m«^ 



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