Contents 15 



chapter page 



33. Parasitism and Pathogenesis; Symbiosis; Commensalism; Gregari- 



OUSNESS AND COMMUNAL LiFE ; PrEDACIOUSNESS ] INSECTIVOROUS 



Plants; Epiphytism; Saprophytism __________ 658 



34. Heredity^ — Genetics ______________ 673 



Definitions and Methods of Studying Genetics _______ 673 



Chromosomes, Polyploidy, and Mitosis _________ 673 



Chromosomal Aberrations _____________ 679 



Genes and Genie Action _____________ 680 



Mendel's Experiments and Laws ___________ 683 



Monohybrid, Dihybrid, and Trihybrid Crosses _______ 686 



Incomplete Dominance ______________ 690 



Multiple Genes and Interaction of Genes _________ 692 



Lethal Genes ___________--_--- 694 



Mutations _ _________________ 695 



Linkage and Crossing Over _____________ 695 



Sex Determination and the Sex Ratio __________ 698 



Sex-Linked Traits ____________--- 699 



Sex-Influenced Traits __ ____________ 703 



Inbreeding and Outbreeding ____________ 703 



Genetic Improvements of Plants and Animals _______ 705 



Production and Maturation of Germ Cells ________ 706 



Inheritance or Noninheritance of Acquired Characters _ _ _ _ - 712 



Human Inheritance _______________ 712 



Eugenics and the Future _____________ 715 



35. Variations and Adaptations in Animals and Plants _ _ _ _ 721 



Importance of Variations _ _ __ _ _ _ _ _ _ _ - _.721 



Classifications of Variations _____________ 722 



Causes of Variations ________________ 726 



Results of Variations ______________ 727 



Adaptations _________________ 727 



36. Living Organisms — Their Origin, Continuity, Development, and 

 Descent With Change _____________ 732 



Origin of Life ________________ 732 



Abiogenesis (Spontaneous Generation) _________ 732 



Biogenesis (Life From Life) ____________ 733 



Origin of Life on the Earth ____________ 733 



Theories for the Origin of Life on the Earth _______ 734 



Continuity of Life _______________ 735 



Development of Living Organisms _-,_______--- 736 



Descent of Organisms With Change (Evolution) _______ 736 



Evidences of Descent With Change _________ 736 



Theories of Descent With Change __________ 746 



37. Biochemical and Biophysical Phenomena ________ 750 



Chemical and Physical Properties of Living Protoplasm "_____ 750 



Atoms and Molecules ___________--- 750 



Electrolytic Dissociation ______________ 751 



Permeability of Membranes and Osmotic Pressure ______ 752 



Diffusion and Conduction _____________ 754 



Surface Tension ___________--_-- 755 



Energy __________________ 756 



Radiant Energy ________________ 757 



Plant and Animal Colorations ____________ 758 



Production and Use of Heat ____________ 760 



Production and Reception of Sound ___________ 761 



