CONTENTS. 



Lecture XL. — The Anisotropy of the Organs of Plants 698 



Definition of Anistropy. — Anistropy a cause of the Configuration of Plants. — Radial 

 Organs are Orthotropic, Dorsi-ventral ones Plagiotropic. — Radial Organs react 

 alike on all sides, Dorsiventral ones differently. — Rolled-up Plagiotropic Organs are 

 Orthotropic— Plagiotropic Lateral Roots. — Shoots of Marchantia. — Plagiotropic 

 Organs consist of Orthotropic parts. — Plagiotropism of the Ivy. — TropcTobini, 

 Gourd, etc. — Torsion in Plagiotropic Lateral Shoots.— Hydrotropism. — Positive 

 and Negative Hydrotropism. 



PART VI.— Reproduction. 



Lecture XLL — The Organs of Reproduction — General Considerations — Algae ; 



Fungi; Archegoniata 721 



Vegetative Multiplication. — Alternation of Generations. — Ascomycetes. — Con- 

 jugatEe. — Gametes. — Zygotes. — Oospheres and Antherozoids (Spermatozoa, Zoo- 

 sperms). — Reproduction of Vauchcria. — Alternation of Generations in the Moss. — 

 Archegonia and Antheridia of the Moss. — Embryo of the Moss. — Reproduction of 

 the Vascular Cryptogams. — Sporangia and Spores of Eqiiisetuni. — Prothallium 

 oi Equisetiii/i. — Embryology of the Fern. 



Lecture XLIL — The Organs of Reproduction, continued. — Heterosporous Vas- 

 cular Cryptogams ; Gymnosperms ; Angiosperms 745 



Reproductive apparatus of Marsilia. — Embryology of Marsilia. — Formation of 

 Embryo inside the Macrospore. — Pollen-grains, Pollen-tube, Embryo-sac. — Naked- 

 seeded Plants. — Nature of the Ovule and of the Seed.— Fertilisation by means of a 

 Pollen-tube. — Development of the Seed in Gymnosperms. — Angiosperms or tnie 

 Flowering Plants. — Flowers of Angiosperms. — Fertilisation of Angiosperms. — Stigma 

 and PoUen-tube.^Seeds with and without Endosperm. — Embrj'ology of Angiosperms. 



Lecture XLIIL — The Action of Sexual Cells upon one another (Continuity of 



Embryonic Substance) ........... 767 



The Essentials of Fertilisation. — Continuity of Embryonic Substance. — Mutual 

 Action at a distance of Sexual Cells. — Strasburger on the Fertilisation of Ferns. — 

 Juranyi on the Fertilisation of CEdogojimm. — Behaviour of Conjugating Gametes. — 

 Action at a distance in PeronosporeK. — Pollen-tubes. 



Lecture XLIV. — Transmission and Blending of the Paternal and Maternal Pro- 

 perties by Fertilisation (Hybrids) 779 



Only nearly allied Forms hybridise.— Mingling of Parental Characters. — Sexuality 

 of Hybrids. — Millardet on the Hybrids of the Vine. — Resistance of Hybrid Vines 

 to the attacks of Fungi and Phylloxera. 



Lecture XLV. — Influence of the Origin of the Sexual Cells of the same species on 



the Result of Fertilisation 787 



Dichogamy, Heterostylism, Herkogamy. — Pollination by the aid of Insects. — Aris- 

 tolochia Clematitis. — Pollination in Salvia. — Pollination in Viola and Epipactis. 



Lecture XLVL — The Object of Fertilisation. Apogamy 798 



Importance of Sexual Organs and Sexual Propagation. — Apogamy. — Vegetative 

 multiplication of Apogamous Plants. 



INDEX 803 



