Bernstein, Aaron, Naturwissenschaftliche Volksbücher, Bd. 17-21, 1897

Table of figures

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[121] Fig. 22.
Page: 509
[122] Fig. 23.
Page: 510
[123] Fig. 24.A B D
Page: 513
[124] Fig. 25.A B C D E F
Page: 515
[125] Fig. 26.
Page: 518
[Figure 126]
Page: 579
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        <div xml:id="echoid-div104" type="section" level="1" n="67">
          <p>
            <s xml:id="echoid-s2206" xml:space="preserve">
              <pb o="12" file="198" n="198"/>
            organiſierten Lebeweſen, d. </s>
            <s xml:id="echoid-s2207" xml:space="preserve">h. </s>
            <s xml:id="echoid-s2208" xml:space="preserve">diejenigen, welche am kom-
              <lb/>
            plizierteſten gebaut ſind, bei denen die Verteilung der mannig-
              <lb/>
            faltigen Lebens-Arbeiten auf viele verſchiedene Organe ſtatt-
              <lb/>
            gefunden hat, am meiſten in ihrem Baue geändert. </s>
            <s xml:id="echoid-s2209" xml:space="preserve">Da eine
              <lb/>
            Veränderung natürlich immer im Anſchluß an das bereits bei
              <lb/>
            den Vorfahren Vorhandene geſchieht, ſo wird ſich oftmals
              <lb/>
            wahrſcheinlich machen laſſen, daß ein beſtimmtes Organ im
              <lb/>
            Verlauf der Generationen durch Umbildung aus einem anderen
              <lb/>
            beſtimmten Organ hevorgegangen iſt, oder, wie die Wiſſenſchaft
              <lb/>
            ſagt, eine
              <emph style="sp">Metamorphoſe</emph>
            (eine Umwandlung oder Ver-
              <lb/>
            wandlung) erlitten hat. </s>
            <s xml:id="echoid-s2210" xml:space="preserve">Wenn wir alſo ſagen: </s>
            <s xml:id="echoid-s2211" xml:space="preserve">die bei einer
              <lb/>
            beſtimmten Art vorhandenen Ranken, welche ſchwächlich ge-
              <lb/>
            baute Gewächſe an widerſtandsfähige Teile zu befeſtigen ver-
              <lb/>
            mögen, ſind metamorphiſierte Blätter reſp. </s>
            <s xml:id="echoid-s2212" xml:space="preserve">Teile von Blättern,
              <lb/>
            und bei einer anderen Art, wie beim Weinſtock u. </s>
            <s xml:id="echoid-s2213" xml:space="preserve">ſ. </s>
            <s xml:id="echoid-s2214" xml:space="preserve">w. </s>
            <s xml:id="echoid-s2215" xml:space="preserve">meta-
              <lb/>
            morphoſierte Sproſſe, ſo ſoll das nach dem Geſagten ein
              <lb/>
            kurzer Ausdruck für die Meinung ſein, daß die Vorfahren der
              <lb/>
            fraglichen Pflanzen an Stelle der Ranken Blätter reſp. </s>
            <s xml:id="echoid-s2216" xml:space="preserve">Sproſſe
              <lb/>
            getragen haben, ſodaß alſo die Ranken im Laufe der Gene-
              <lb/>
            rationen aus dieſen Organen hervorgegangen wären.</s>
            <s xml:id="echoid-s2217" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s2218" xml:space="preserve">Bei einer Pflanze, bei welcher wir in dieſer Weiſe die
              <lb/>
            Entſtehung eines Organes b aus einem Organ a annehmen
              <lb/>
            dürfen, nennen wir dieſe Organe
              <emph style="sp">homolog</emph>
            ; </s>
            <s xml:id="echoid-s2219" xml:space="preserve">wo wir z. </s>
            <s xml:id="echoid-s2220" xml:space="preserve">B.
              <lb/>
            </s>
            <s xml:id="echoid-s2221" xml:space="preserve">anzunehmen berechtigt ſind, daß Ranken im Verlaufe der Gene-
              <lb/>
            rationen aus Blättern hervorgegangen ſind, nennt man die
              <lb/>
            Ranken und Blätter gleichwertig (homolog).</s>
            <s xml:id="echoid-s2222" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s2223" xml:space="preserve">Sage ich alſo, Ranke und Blatt oder Ranke und Sproß
              <lb/>
            ſind einander homolog, ſo bleibt es ungewiß, welches von den
              <lb/>
            beiden Organen aus dem anderen hervorgegangen iſt. </s>
            <s xml:id="echoid-s2224" xml:space="preserve">In
              <lb/>
            dieſem Falle kann man jedoch Gründe für die erſterwähnte
              <lb/>
            Auffaſſung beibringen, indem Ranken den Pflanzen nicht all-
              <lb/>
            gemein zukommen und die am komplizierteſten gebauten Arten
              <lb/>
            vorwiegend ſpäter entſtanden ſind als weniger hoch organiſierte.</s>
            <s xml:id="echoid-s2225" xml:space="preserve"/>
          </p>
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