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Biology Today and Tomorrow
Cecie Starr
Christine A. Evers
Lisa Starr
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Biology: Today & Tomorrow, Sixth Edition
Cecie Starr, Christine A. Evers, Lisa Starr
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Regulation of Body Temperature 432 Hypothermia and Hyperthermia 433
21 How Animals Move
21.1 Bulking Up Muscles 437
21.2 Skeletal Systems 438
Invertebrate Skeletons 438
The Vertebrate Endoskeleton 439
Bone Structure and Function 439 Where Bones Meet—Skeletal Joints 440
21.3 Skeletal Muscles 442 Moving Bones 443
Moving Other Tissues 443
21.4 How Muscle Contracts 443
Components of Skeletal Muscle 443
The Sliding Filament Model 444
21.5 Fueling Muscle Contraction 445
Energy-Releasing Pathways 445
Types of Skeletal Muscle Fibers 446
21.6 Exercise and Inactivity 447
Benefits of Exercise 447
Effects of Inactivity 447
22 Circulation and Respiration
22.1 A Shocking Save 451
22.2 Circulatory Systems 452
Circulatory Systems 452
Vertebrate Circulatory Systems 453
22.3 Human Cardiovascular System 454
Pulmonary Circuit 454
Systemic Circuit 454
22.4 The Human Heart 455
The Cardiac Cycle 456
Electrical Signals in the Heart 456
22.5
Blood 457
Components of Blood 457
Clotting 458
Blood Transfusions and Banking 458
22.6 Blood Vessel Form and Function 459
Blood Pressure 459
From the Heart to Tissues 459
Capillary Exchange in Tissues 460
Return to the Heart 461
22.7 Cardiovascular Disorders 461
Hypertension 461
Atherosclerosis 461
22.8 Animal Respiratory Systems 463
Two Sites of Gas Exchange 463
Respiratory Organs 463
22.9 Human Respiratory Function 465
The Respiratory Tract 465
Breathing 466
Gas Exchange and Transport 466
Respiratory Disorders 467
25.5 The Central Nervous System 529
The Blood–Brain Barrier 530
Regions of the Human Brain 530
A Closer Look at the Cerebral Cortex 531
The Spinal Cord 532
Spinal Cord Injury 532
25.6 The Peripheral Nervous System 533
Somatic Nervous System 533
Autonomic Nervous System 534
25.7 The Senses 535
Sensory Reception and Diversity 535
The Chemical Senses 536
Light and Vision 537
Hearing 540
Sense of Balance 542
The Somatosensory Cortex 543
26 Endocrine Control
26.1
Endocrine Disrupters 547
26.2 Hormone Function 549
Types of Hormones 549
Hormone Receptors 551
26.3 The Hypothalamus and Pituitary Gland 552
The Hypothalamus and Pituitary Gland 552
Posterior Pituitary Function 552
Anterior Pituitary Function 552
Growth Hormone Disorders 553
26.4 The Pineal Gland 555
Daily and Seasonal Cycles 555
Light at Night as an Endocrine Disrupter 555
26.5 Thyroid and Parathyroid Glands 556
The Thyroid Gland 556
The Parathyroid Glands 558
26.6 The Pancreas 558
Controlling Blood Glucose 559
Diabetes Mellitus 559
26.7 The Adrenal Glands 561
Feedback Control of Cortisol Secretion 561
Hormonal Response to Stress 562
Cortisol-Related Disorders 562
26.8 Sex Hormones 563
27 Animal Reproduction and Development
27.1 Assisted Reproductive Technology 567
27.2 Modes of Reproduction 568
Asexual Reproduction 568
Sexual Reproduction 568
Variations on Sexual Reproduction 568
27.3 Stages of Animal Development 569
Gametes Form and Unite 569
Cleavage 569
Gastrulation 570
Tissues and Organs Form 571
27.4 The Human Reproductive System 571
Female Reproductive Anatomy 571
The Ovarian Cycle 572
The Menstrual Cycle 573
Male Reproductive Anatomy 575
How Sperm Form 576
27.5 Bringing Gametes Together 577
Sexual Intercourse 577
A Sperm’s Journey 577
Fertilization 578
27.6 Human Development 579
From Cleavage to Implantation 579
Fetal Development 581
Functions of the Placenta 582
Maternal Effects on Prenatal Development 582
27.7 Birth and Lactation 583
Childbirth 583
Surgical Delivery 583
Nourishing the Newborn 583
27.8 Fertility and Reproductive Health 584
Contraception 584
Infertility 585
Sexually Transmitted Diseases 586
Protists 586
Bacteria 586
Viruses 587
Unit 6 H ow P l A nts work
28 Plant Form and Function
28.1 Leafy Cleanup Crews 591
28.2 Tissues in a Plant Body 592
The Plant Body 592
Plant Tissues 592
Eudicots and Monocots 595
28.3 Stems and Leaves 596
Stems 596
Stem Specializations 597
Leaves 598
28.4 Roots 600
External Structure 600
Internal Structure 600
Uptake of Water and Nutrients 600
Microbial Partners 601
28.5 Fluid Movement in Plants 602
Water Wicks through Xylem 602
Sugars Flow through Phloem 604
28.6 Patterns of Growth 605
Primary Growth 605
Secondary Growth 606
29 Life Cycles of Flowering Plants
29.1 Plight of the Honeybee 611
29.2 Flower Structure and Function 612
Floral Structure 612
Pollination 613
29.3 Sexual Reproduction in the Flowering Plant 615
The Female Gametophyte Forms 616
The Male Gametophyte Forms 616
Gametophytes Meet 616
29.4 Seeds and Fruits 618
Seeds 618
Fruits 618
29.5 Early Development 620
Breaking Dormancy 620
Early Growth Patterns 620
29.6 Asexual Reproduction in Plants 622
Agricultural Applications 622
29.7 Plant Hormones 623
Cell-to-Cell SIgnaling in Plants 623
Auxin 624
Cytokinin 625
Gibberellin 625
Abscisic Acid 626
Ethylene 626
29.8 Growth Responses 628
Movement 628
Daily Changes 630
Seasonal Changes 630
Appendix I Answers to Self-Quizzes 634
Appendix II Periodic Table of the Elements 637
Appendix III A Plain English Map of the Human Chromosomes 638
Glossary 639
Index 652
patterns of protein secondary structure; prion structure changes. New Critical Thinking question about how using palm oil as a substitute for PHOs is exacerbating deforestation. Closer Look feature: How protein structure arises.
3 Cell Structure New content includes theory of living systems; discussion of nuclear pores, tau tangles, and Alzheimer’s disease. New tables: eukaryotic organelles; collective properties of living systems. New photographs: micrographs of gut microbiota, nuclear membrane, and basement membrane. New Critical Thinking question about why some meat contaminated with toxic strains of bacteria is not safe to eat even after cooking. Closer Look features (2): Some interactions among components of the endomembrane system; cell junctions in animal tissues.
4 Energy and Metabolism New content: how heavy drinking causes fatty liver; fluid balance in the body. New figures: feed conversion ratio; comparing activation energy in energy-releasing and energy-requiring reactions; enzymes lower activation energy; firefly luciferase. New Critical Thinking question about the alcohol flushing reaction and alcohol metabolism. Closer Look feature: Examples of membrane-crossing mechanisms.
5 Photosynthesis For this edition, expanded material on photosynthesis and respiration has been separated into two chapters. New overview section includes discussion of autotrophs, heterotrophs, and stomata function. Other new content: special pairs; bacteria that carry out infrared photosynthesis; increased efficiency of the Calvin–Benson cycle in engineered plants. New Digging Into Data activity about CO2 emissions from fossil fuels. New figures include atmospheric CO2 level over the last 800,000 years; correlation between atmospheric CO2 content and temperature since 1880; how photosynthesis sustains life; correlation between light wavelength and energy; red algae (photosynthetic pigment adaptation). New research correlating wildfire severity with rising global temperatures is included with a stunning photo of the 2018 Mendocino complex wildfire. Closer Look feature: Light-dependent reactions of photosynthesis, noncyclic pathway.
6 Respiration New content includes Application about mitochondrial diseases, cellular respiration, and oxidative stress; introductory section comparing aerobic respiration with fermentation; glycolysis reactions; ketogenic diet mechanism. New figures: glycolysis reactions, alcoholic fermentation reactions; lactate fermentation reactions. New Digging Into Data activity about the reprogramming of brown fat mitochondria by dietary fat overload. Closer Look features (2): Aerobic respiration continues in mitochondria; food to energy.
7 DNA Structure and Function New content includes introduction to PCR; expanded material on mutations includes dosedependent DNA damage by ionizing radiation, and cancercausing chemicals in foods and industrial/household products. New figures: components of a nucleotide; micrographs of DNA
packing; mutated flowers from Chernobyl. Closer Look feature: DNA packing in eukaryotic chromosomes.
8 From DNA to Protein New content includes concepts of coding and noncoding strands; a beneficial hemoglobin mutation (HbC); and expanded material on epigenetics. New art: how transcription copies a gene into RNA form; comparison of uracil/thymine and ribose/deoxyribose; how transcription produces an RNA copy of a gene; RNA polymerase binding to promoter; alternative splicing; surface renders of ribosome subunits; effect of a mutation in a regulatory site; points of control over gene expression; replication of methylated DNA. New table compares features of DNA and RNA. Closer Look feature: Translation.
9 How Cells Reproduce New content includes current research and paradigms on cytoplasmic division and senescence; concept of polygenic inheritance; Mary Claire-King’s discovery of BRCA1. New figures: micrograph showing mitosis in a human embryo; micrograph of mitotic spindle; fluorescence micrographs of checkpoint proteins; different modes of reproduction; meiosis halves the chromosome number, and fertilization restores it. New table comparing asexual and sexual reproduction. New Critical Thinking question about HPV and cancer. Closer Look features (2): Mitosis; meiosis.
10 Patterns of Inheritance New content includes current paradigms for CF, Huntington’s, progeria, Tay–Sachs, and DMD; and concept of developmental flexibility in plant phenotype. New photos: cells lining trachea; seasonal changes in plants; albino iris; IVF. Closer Look feature: Breeding experiments with the garden pea.
11 Biotechnology New content includes forensic genealogy case; AquAdvantage Salmon; mechanism, applications, and social implications of CRISPR gene editing. New figures: Exponential amplification of DNA by PCR; photo of Golden Rice; example of CRISPR gene editing. New table lists human genome statistics. Closer Look feature: An example of cloning.
12 Evidence of Evolution Cetacean evolutionary sequence updated to reflect currently accepted narrative. New art: photo of Dorudon atrox fossil; stem reptile; plate tectonics; paleogeography Mercatur projections. Closer Look feature: Geologic time scale correlated with sedimentary rock in the Grand Canyon.
13 Processes of Evolution New content includes updated material on antibiotic resistance and overuse of antibiotics in livestock; forensic phylogenetics case; phylogeny of ST131 superbug. New figures: photos of variation in earlobe attachment; genetic drift, bottleneck, and the founder effect; evolution of ST131. Art updates to reflect current research: HbS allele frequency vs. incidence of malaria; sympatric speciation in wheat. New Critical Thinking question about the EPA’s 2019 approval of medically important antibiotics in the treatment of citrus greening disease. Closer Look feature: How reproductive isolation prevents interbreeding.
14 Prokaryotes, Protists, and Viruses Updated information about the role of the human microbiome in health and disease and the
proposed fossil evidence of early life. Increased emphasis on the ecological importance of bacteria. Updated figures illustrating binary fission and bacteriophage replication. New information about antibiotic mechanisms. Discussion of protists now organized around ecology, rather than phylogeny. New Critical Thinking questions about the human virome, and the effects of pesticides on pollinator microbiomes. Closer Look feature: Replication of HIV.
15 Plants and Fungi Updated figures depicting plant and fungal life cycles. New table compares plant, fungal, and animal traits. New figure illustrating the hyphae in a mushroom. New photo of peat bog. Updated information about white-nose syndrome in bats. New Critical Thinking question about plant defenses against wheat stem rust. Closer Look features (2): Moss life cycle; fern life cycle.
16 Animal Evolution New content about and photo of the oldest known fossil animal. New graphic of sea star anatomy. Updated discussion of early H. sapiens migrations. New Critical Thinking question about medicinal compounds derived from spider venom. Closer Look feature: One model of human evolution.
17 Population Ecology New content about human overharvesting of horseshoe crabs lowering the carrying capacity of the environment for migratory red knot sandpipers. Updated nationbased age structure diagrams. New Critical Thinking questions, estimating size of a Canada goose population, predation on horseshoe crabs, effect of house sparrow introduction on bluebird populations, factors affecting human population growth. Closer Look feature: Logistic growth.
18 Communities and Ecosystems Revised table better depicts the variety of interspecific interactions. New content includes biological pest control, biological accumulation and magnification of toxins, nutrient pollution and algal blooms, and ocean acidification. Updated coverage of the rise in atmospheric carbon dioxide and added information about the data that indicate this increase is a result of fossil fuel use. New Critical Thinking questions about studying the history of the atmosphere and pollutant accumulation in marine mammals. Closer Look feature: The nitrogen cycle.
19 The Biosphere and Human Effects New opening Application about the decline of monarch butterflies. Content reorganized: Deforestation discussed with forest biomes, desertification with desert biomes. New content includes current threats to Brazilian rainforest. Updated coverage of acid rain, ozone depletion, and biodiversity hot spots. New Digging Into Data activity about marine plastic pollution. New Critical Thinking questions about preserving monarch butterflies, effects of ozone depletion on phytoplankton, and how Brazilian deforestation alters local climate.
20 Animal Tissues and Organs New content includes carcinomas, hyperthermia, and hypothermia. Revised figure illustrating
thermal homeostasis. New Critical Thinking questions about inducing fibroblasts to become pluripotent, organelle abundance in secretory epithelia, effects of vitamin C deficiency on tissues, and benefits of epithelia turnover. Closer Look feature: Structure of human skin.
21 How Animals Move Revised art depicting actin-myosin interactions. New content includes joint injuries and disorders, creatine supplementation. New Critical Thinking question about effects of prolonged sitting. Closer Look feature: Actin-myosin interaction.
22 Circulation and Respiration New content includes blood transfusions and blood banking, strokes, sleep apnea, and health effects of smoking marijuana and of vaping. New Data Analysis question compares effects marijuana and tobacco smoking on lung function. New Critical Thinking questions about “canary in a coal mine,” hands-only cardiac resuscitation, and artificial hemoglobin. Closer Look feature: Capillary exchange.
23 Immunity New content includes use of antibodies in research; CAR T cell therapy; role of keratinocytes as immune cells in contact allergies; lymphocyte maturation. Much-expanded material on herd immunity, with narrative about an unvaccinated child contracting measles. New photos: macrophages attacking parasitic worm; Pap smear comparison; bacteria on mobile phone; mast cell in situ; oral bacteria on a cheek cell; complement pore; phagocytosis of fungal cells by a dendritic cell; immunofluorescence; cell-to-cell transmission of HIV; baby with measles. New art: antigen display by MHC molecules. New table comparing antibody-mediated and cell-mediated responses. New Critical Thinking questions: Different types of vaccine preparations; CAR T cell therapy. Closer Look features (3): Example of inflammation as a response to bacterial infection; an example of an antibody-mediated response; an example of a cellmediated response.
24 Digestion and Excretion New content includes discussion of screening methods for obesity, role of the microbiota in digestive health and disease, and importance of basal metabolic rate. New Critical Thinking questions about obesity-related alleles and paying kidney donors. Closer Look feature: How urine forms.
25 Neural Control and the Senses Updated information about concussions in football players. New content about neuromodulators, fibromyalgia. Simplified figure comparing sympathetic and parasympathetic effects. Revised figures depicting action potential, visual accommodation, organization of the retina. New Critical Thinking questions about head injury, loss of sweetness receptor in carnivores, pain perception in insects, and effects of alcohol on the cerebellum. Closer Look feature: Action potential.
26 Endocrine Control Improved illustration of pituitary function. New content includes hormonal effects of BPA (bisphenol A), phthalates, and light pollution; discovery of insulin. New Critical Thinking questions about action of endocrine disruptors,
phthalates and developmental delays, climate change and seasonal hormonal changes. Closer Look feature: Two mechanisms of hormone action.
27 Animal Reproduction and Development New content about surgical deliveries. Improved figure showing changes in hormone levels during the female reproductive cycles. Contraception, infertility, and STDs now covered in a final section. New Critical Thinking questions about IVF and female infertility. Closer Look feature: Hormones and the female reproductive cycle.
28 Plant Form and Function New content includes use of sunflowers in phytoremedation of Hiroshima, Chernobyl, and Fukushima. New art shows external structure of monocot and eudicot stems.
New Critical Thinking question about hyperaccumulators in phytoremediation. Closer Look features (3): Internal structure of a typical eudicot leaf; cohesion–tension theory; and translocation of sugars in phloem from source to sink.
29 Plant Reproduction and Development New content includes role of Varroa mites and deformed wing virus in CCD; nastic movements. New photos: Varroa mite on honeybee; pollinators sharing pathogens; embryonic leaves in a peanut; monocot embryo; and Venus flytrap capturing a fly. Detail added to plant life cycle art for accuracy. New Critical Thinking question about the keruru as the last surviving dispersal agent for puriri seeds. Closer Look feature: Life cycle of a typical eudicot.
ACAD e M i C ADV isors
We owe a special debt to the following members of our advisory committee for helping us shape the book’s content. We appreciate their guidance.
Andrew Baldwin, Mesa Community College
Gregory A. Dahlem, Northern Kentucky University
Terry Richardson, University of North Alabama
Previous Edition advisory members:
Charlotte Borgeson, University of Nevada, Reno
Gregory Forbes, Grand Rapids Community College
Hinrich Kaiser, Victor Valley Community College
Lyn Koller, Embry-Riddle Aeronautical University
We also wish to thank the following reviewers:
Idris Abdi, Lane College
Susan L. Bower, Pasadena City College
James R. Bray Jr., Blackburn College
Randy Brewton, University of Tennessee
Steven G. Brumbaugh, Green River Community College
Jean DeSaix, University of North Carolina
Brian Dingmann, University of Minnesota, Crookston
Hartmut Doebel, The George Washington University
Johnny El-Rady, University of South Florida
Patrick James Enderle, Georgia State University
Ruhul H. Kuddus, Utah Valley State College
Dr. Kim Lackey, University of Alabama
Catarina Mata, Borough of Manhattan Community College
Timothy Metz, Campbell University
Alexander E. Olvido, University of North Georgia
Michael Plotkin, Mt. San Jacinto College
Nathan S. Reyna, Oachita Baptist University
Laura H. Ritt, Burlington County College
Erik P. Scully, Towson University
Jennifer J. Skillen, Sierra College
Previous Edition Reviewers:
Meghan Andrikanich, Lorain County Community College
Lena Ballard, Rock Valley College
Barbara D. Boss, Keiser University, Sarasota
Mimi Bres, Prince George’s Community College
Evelyn K. Bruce, University of North Alabama
Chantae M. Calhoun, Lawson State Community College
Thomas F. Chubb, Villanova University
Julie A. Clements, Keiser University, Melbourne
Francisco Delgado, Pima Community College
Elizabeth A. Desy, Southwest Minnesota State University
Josh Dobkins, Keiser University, online
Pamela K. Elf, University of Minnesota, Crookston
Jean Engohang-Ndong, BYU Hawaii
Ted W. Fleming, Bradley University
Edison R. Fowlks, Hampton University
Martin Jose Garcia Ramos, Los Angeles City College
J. Phil Gibson, University of Oklahoma
Judith A. Guinan, Radford University
Carla Guthridge, Cameron University
Laura A. Houston, Northeast Lakeview–Alamo College
Robert H. Inan, Inver Hills Community College
Dianne Jennings, Virginia Commonwealth University
Ross S. Johnson, Chicago State University
Susannah B. Johnson Fulton, Shasta College
Paul Kaseloo, Virginia State University
Ronald R. Keiper, Valencia Community College West
Dawn G. Keller, Hawkeye Community College
Vic Landrum, Washburn University
Lisa Maranto, Prince George’s Community College
Kevin C. McGarry, Keiser University, Melbourne
Ann J. Murkowski, North Seattle Community College
Joshua M. Parke, Community College of Southern Nevada
Elena Pravosudova, Sierra College
Carol Rhodes, Cañada College
Todd A. Rimkus, Marymount University
Lynette Rushton, South Puget Sound Community College
Marilyn Shopper, Johnson County Community College
Jim Stegge, Rochester Community and Technical College
Lisa M. Strain, Northeast Lakeview College
Jo Ann Wilson, Florida Gulf Coast University
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A C knowle DGM ents
Writing, revising, and illustrating a biology textbook is a major undertaking for two full-time authors, but our efforts constitute only a small part of what is required to produce and distribute this one. We are truly fortunate to be part of a huge team of very talented people who are as committed as we are to creating and disseminating an exceptional science education product.
Biology is not dogma; paradigm shifts are a common outcome of the fantastic amount of research in the field. Ideas about what material should be taught and how best to present that material to students changes from one year to the next. It is only with the ongoing input of our many academic reviewers and advisors (previous page) that we can continue to tailor this book to the needs of instructors and students while integrating new information and models. We continue to learn from and be inspired by these dedicated educators.
On the production side of our team, the indispensable Lori Hazzard orchestrated a continuous flow of files, photos, and illustrations while managing schedules, budgets, and whatever else happened to be on fire at the time. Lori, thank you for your patience and dedication. Thank you also to Ragav Seshadri, Kelli Besse, and Christine Myaskovsky for your help with photoresearch. Copyeditor Heather McElwain and proofreader Heather Mann, your valuable suggestions kept our text clear and concise.
Thanks to Cengage’s Product Manager Katherine Caudill-Rios, Content Manager Brendan Killion, and In-House Subject Matter Expert Katherine Scheibel.
Lisa Starr and Christine Evers
Cengage acknowledges and appreciates Lisa Starr’s contribution of more than 300 pieces of art to this edition.
Tom McHugh/Science Source
Invitation to Biology
1.1 The Secret Life of Earth 3
1.2 Life Is More Than the Sum of Its Parts 4
1.3 How Living Things Are Alike 6
1.4 How Living Things Differ 8
1.5 The Science of Nature 12
1.6 Analyzing Experimental Results 17
1.7 The Nature of Science 20
The cloud forest that covers about 2 million acres of New Guinea’s Foja Mountains is extremely remote and difficult to access, even for native people of the region. Explorers are still discovering new species in it.
Con C ept Conne C tions
Whether or not you have studied biology, you already have an intuitive understanding of life on Earth because you are part of it. Every one of your experiences with the natural world—from the warmth of the sun on your skin to the love of your pet—has contributed to that understanding. The organization of this book parallels nature’s levels of organization, from atoms to the biosphere. Learning about the structure and function of atoms and molecules will prime you to understand how living cells work. Learning about processes that keep a single cell alive can help you understand how multicelled organisms survive. Knowing what it takes for organisms to survive can help you see why and how they interact with one another and their environment.
Tim Laman/National Geographic Image Collection.
Other documents randomly have different content
réjouit d'avoir rencontré Lansade, trouva que Mme Morin était une excellente femme, et lui voua une reconnaissance éternelle. Cependant il se demanda pourquoi cette Parisienne avait écrit sur son livre qu'il était chasseur de profession. Il songeait aussi à l'embarras du marchand de porcelaine, fermant sa boutique et ne sachant pas, après trente ans, reconnaître quel était le volet qui devait être placé le premier. Cela l'amena à penser à la sagacité des sauvages qui, au milieu d'une forêt, reconnaissent à la manière dont un brin d'herbe se trouve courbé quel est l'ennemi qu'ils ont à redouter... Il chercha de quel côté était la supériorité et il s'endormit sans avoir trouvé.
tout le globe une infinité de produits désastreux. Ce peuple absurde n'avait, il faut en convenir, qu'une mission à accomplir sur terre: cultiver le thé et fabriquer des tasses dans lesquelles on puisse le boire. Trompant les desseins de la Providence, il nous a saturé d'un tas de petits monstres verts et bleus, d'ivoire ciselé, de laque, de nankin, de savon triangulaire et d'allumettes odoriférantes. Cela estil vrai, oui ou non? Eh bien, j'aurais pardonné les potiches, les magots, la laque, cette espèce de cire à cacheter les lettres écrites à l'encre de Chine, l'étoffe jaune, les allumettes, le savon à écorcher; j'aurais tout pardonné à ces brutes qui tuent nos prêtres et jettent leurs enfants dans les ruisseaux, s'ils n'avaient pas inventé les proverbes.
Oh! les proverbes! mistress Héléna, vous ne savez pas ce que c'est, je vous assure. Figurez-vous les choses du monde les plus sottes et les plus ennuyeuses, et vous n'approcherez pas.
Imaginez sept ou huit mille pensées décousues et se contredisant toutes, imprimées en caractères honteux de servir une si triste cause, sur du papier à chandelles, et vous aurez une faible idée de ce que nous autres Français, nous appelons la SagessedesNations.
Ouvrez la première page, vous y lirez les phrases que voici:
«Il ne faut jamais courir deux lièvres à la fois.»
«Il faut toujours avoir deux cordes à son arc.»
«Il ne faut jamais remettre au lendemain ce qu'on peut faire la veille.»
«Le sage remue sa langue sept fois avant de parler.»
«Faute d'un moine l'abbaye ne manque pas.»
«La mort d'un ciron fait un vide dans l'univers.»
«Les paroles s'envolent, les écrits restent.»
Voilà, chère madame, les échantillons les plus profonds de cette profonde sagesse.
»Ma belle-mère a tort; elle se mêle de ce qui ne la regarde pas.
»J'ai envie de changer mon coupé.»
Si, au lieu de rester une seconde pour se transformer, l'homme mettait une heure, il aurait tout le temps nécessaire pour réfléchir:
Qu'il aurait tort d'aller voir Jeanne qui le ruine; que d'ailleurs sa femme est charmante et mille fois plus belle et plus spirituelle que Jeanne, qui est une grue, qui se peint le visage;
Qu'il aurait tort d'acheter du Mobilier, parce que s'il est vrai que le Mobilier hausse quelquefois, il est vrai aussi qu'il baisse souvent;
Qu'il aurait tort de ne pas prêter vingt-cinq louis à Dubief, qui est un honnête garçon qui lui a rendu des services;
Qu'il aurait tort de repasser ses mauvaises actions de trois étoiles à Mongoville, ce qui serait un vol;
Qu'il aurait tort de faire un procès à Tournade, parce que les gens de justice, huissiers et autres avoués en profiteraient seuls; puis Tournade a de la famille, que diable!
Qu'il aurait tort de faire une scène à sa belle-mère, parce qu'enfin une mère a bien un peu le droit de se mêler des affaires de sa fille;
Qu'il aurait tort de changer sa voiture, parce que si le malheur voulait qu'il fasse faillite, ce qui pourrait bien lui arriver, ses créanciers lui reprocheraient amèrement son luxe.
Toutes ces réflexions faites, il passerait son habit, et tout irait pour le mieux dans la vie de ce galant homme et de ses semblables qui agiraient comme lui.
Vous voyez, mistress, que devant un si immense résultat, l'emploi d'un mot inconvenant est une bien petite affaire, et que vous ne sauriez me refuser votre pardon.
Vous allez me dire que ce conseil, cet avis, cet aphorisme auquel je voudrais donner force de loi, ne concernant que les hommes, vous déclarez vous en laver les mains. Attendez, j'ai aussi à donner aux
XI
Cinq heures sonnèrent. Eusèbe fit le signe de la croix, bien persuadé que les trois coups de l'angelus allaient se faire entendre; il écouta vainement.
—Voici l'heure, se disait-il, où mon père se lève et va courir les champs, vivre avec la nature. Pierre étrille les chevaux; la grande Caty vend le lait à la ville, et monsieur le curé du Moustier est en train de dire sa messe. Ici, tout dort. Est-ce le progrès qui retarde ou la routine qui avance?
Ne pouvant résister au désir de voir la ville, le jeune homme descendit doucement, trouva la porte de la rue ouverte et sortit.
Ce serait ici le moment de faire une description rapide des boulevards de Paris à six heures du matin et de dépeindre les étonnements et les déceptions du jeune provincial.
Malheureusement, les descriptions apprennent peu ou point à ceux qui les lisent, et donnent beaucoup de peine à ceux qui les font. Puis, si elles reposent le lecteur, il faut convenir qu'elles lui donnent de mauvaises habitudes, entre autres celle de poser sur leur table de nuit le volume qu'ils ont dans la main et de s'endormir.
Eusèbe Martin n'eut ni déception ni étonnement. Il avait rêvé dans ses champs une ville en or, pavée de rubis et d'émeraudes. Il trouvait à la place un amas de pierres et de boue. Il en avait pris son parti. Quand il eut bien marché sans regarder, et bien regardé sans voir, il songea que ce qu'il avait de mieux à faire était d'aller consulter son ami le marchand voltairien, qui ne manquerait pas de lui donner de bons avis.
Lansade reçut le jeune homme à bras ouverts et le retint à déjeuner. Aussitôt à table, il le questionna cordialement.
—Voyons, mon jeune ami, je n'ai pas voulu hier soir être indiscret ou aggraver vos ennuis en vous demandant au juste ce que vous veniez faire à Paris; mais j'espère que, puisque vous me demandez des conseils, vous allez me dire véritablement quelles sont vos intentions et votre but.
Je vous l'ai dit, mon cher Lansade, je suis venu visiter la capitale du monde civilisé, pour apprendre la vie, étudier la civilisation, et, si cela est possible, chercher où se trouve le vrai, apprendre à distinguer le faux, et aussi pour obéir à mon père.
—A dire vrai, répondit Lansade, je ne comprends pas un mot de ce que vous me dites. Pour apprendre la vie, il n'y a qu'un moyen, il faut vivre. Pour étudier la civilisation, vous n'aviez pas besoin de venir si loin: elle est partout. Croyez-vous que Limoges soit peuplé de sauvages? On y trafique aussi bien qu'ailleurs, peut-être mieux. La civilisation, voyez-vous, c'est le commerce, et pas autre chose; le vrai, c'est le travail.
Eusèbe répondit:
Je travaillerai.
XII
Le marchand voltairien avait fort applaudi à la résolution prise par le jeune homme.
—Mais que ferez-vous? lui demanda-t-il.
Eusèbe lui avoua qu'il était fort embarrassé pour répondre à cette question. Lansade reprit:
Vous réfléchirez. Passez quelques jours à vous distraire, à voir Paris. Vous ferez des connaissances. De mon côté, je chercherai, je trouverai peut-être quelque chose qui pourra vous convenir.
Un jeune homme à la figure souriante entra dans le magasin.
—Que Dieu répande sur vous ses grâces, monsieur Lansade, bonjour. Voici vos deux vases; comment trouvez-vous ça? Est-ce assez touché?
—Très-bien, dit le marchand après avoir attentivement considéré les peintures qui, en vieux style, ornaient les deux objets que lui portait le nouveau venu; très-bien, monsieur Buck. Quand vous voulez vous en donner la peine, vous faites mieux que personne. Tenez, voici vingt-cinq francs, faites-moi un reçu.
—Une livre sterling! Voilà certes un prix qui n'est pas excessif, cher monsieur Lansade, et vous me demandez un reçu par-dessus le marché, cela dépasse les bornes. Enfin, que voulez-vous, puisqu'il faut en passer par là, donnez-moi une plume et du papier. Si jamais je deviens un peintre célèbre, ce qui est certain, vous aurez là un autographe qui vaudra de l'or.
—Tant mieux, répondit le marchand, tant mieux pour moi, et tant mieux aussi pour vous, n'est-ce pas, monsieur Buck?
—Tant mieux pour les deux, c'est entendu, dit le peintre.
