xii CONTENTS 



CHAPTER PAGE 



tory System — Reproductive System — Female — Male — Propagation 

 Rate in Mammals — Periods of Gestation — Nervous System and Sense 

 Organs — A Triumph of Coordination — Fatigue in the Nerve Cell — 

 Regeneration in the Nervous System — Hibernation and Aestivation 

 Organs that Man Can Lose — Statistics of Vitality — Susceptibility 

 of Mammals to Poison. 



XXI — Social Life of Animals 482 



Association of Different Species — Living Free — Commensalism — Sym- 

 biosis — Parasitism — Effects of Parasitism — On Parasite — On Host — 

 Association of the Same Species — Colonies — Communities — Gregari- 

 ousness — Polygyny and Polyandry — Cases in which the Sexes Live 

 Apart — Societies Composed of Different Species — Monogamy — Sea- 

 sonal Mateships — Types of Families — Parent Families — Father 

 Families — Mother Families — Child Families — References on Animal 

 Relationships — Protection — Masking — Color Resemblance — Mimicry 

 — Geographical Distribution— Barriers — Salinity of Water^ — Water 

 Supply — Depth of Water — Temperature — Mountain Ranges — Do- 

 mestication of Animals — Dog — Cat — Horse — Donkey — Pig — Cattle — 

 Goat— Sheep — Rabbits — Pigeons— Fowls — Ducks — Geese — Peacocks 

 — ^Turkeys — Tissue Survival Outside of the Body — Longevity of Ani- 

 mals — Mammals — Birds — Reptiles — Amphibia — Fishes — Arthro- 

 poda — MoUusca — Annelida — Coelenterata — Pulse Frequency. 



XXII — Evolution, Heredity, Eugenics 499 



Cell Division — Amitosis — Mitosis — Oogenesis — Spermatogenesis — Fer- 

 tilization — Theories of Heredity and Evolution — History of the Evolu- 

 tionary Idea — What we owe to Charles Darwin — Examples of Men- 

 delian Inheritance in Man — The Origin of Species according to 

 Lamarck, Darwin, Weismann, Mendel and DeVries — Evidences for 

 the Theory of Evolution — i. Morphology — 2. Classification — 3. 

 Blood Tests — 4. Embryology — 5. Paleontology — 6. Geographic Dis- 

 tribution — Sex Determination — Sex Linked Characters — Crossing Over 

 — Genes — Lethal Factors — Physiological Basis — Parthenogenesis — 

 Identical versus Fraternal Twins — Hermaphroditism and the Free 

 Martin — Hen Feathering in the Sebright Bantam — Evidence for and 

 against the Inheritance of Acquired Characters — Inheritance of 

 Disease — i. Prenatal Infection — 2. Prenatal Injury to the Germ Cells 

 or Embryo — 3. Inheritance of Weakness Predisposing to Disease — 

 4. Inheritance through the Germinal Substance — Maternal Impres- 

 sions — Eugenics. 



