Bernstein, Aaron, Naturwissenschaftliche Volksbücher, Bd. 12-16, 1897

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        <div xml:id="echoid-div55" type="section" level="1" n="53">
          <p>
            <s xml:id="echoid-s2129" xml:space="preserve">
              <pb o="31" file="0163" n="163"/>
            ziehung wichtig geworden iſt. </s>
            <s xml:id="echoid-s2130" xml:space="preserve">Zu dieſem Zweck öffnet man
              <lb/>
            einem Tier eine Schlagader und bringt die Öffnung mit einem
              <lb/>
            Gummiſchlauch in Verbindung, der in ein Glasrohr führt.
              <lb/>
            </s>
            <s xml:id="echoid-s2131" xml:space="preserve">Dieſes Glasrohr iſt wie ein lateiniſches U gebogen, das heißt,
              <lb/>
            es beſteht aus zwei aufrecht ſtehenden Säulen, die unten mit
              <lb/>
            einander in Verbindung ſtehen. </s>
            <s xml:id="echoid-s2132" xml:space="preserve">In das Rohr wird Queck-
              <lb/>
            ſilber hineingegoſſen, das vor dem Verſuch in beiden Säulen
              <lb/>
            gleich hoch ſteht. </s>
            <s xml:id="echoid-s2133" xml:space="preserve">Bei dem Verſuch wird der Gummiſchlauch,
              <lb/>
            der an einem Ende mit der Ader in Verbindung ſteht, mit dem
              <lb/>
            andern Ende auf die eine Öffnung des Glasrohrs gebracht. </s>
            <s xml:id="echoid-s2134" xml:space="preserve">
              <lb/>
            Das Blut ſtürzt aus der geöffneten Ader durch den Gummi-
              <lb/>
            ſchlauch in das Glasrohr und drückt auf das Queckſilber, ſo
              <lb/>
            daß es in der andern Säule in die Höhe ſteigt, und je nach
              <lb/>
            der Höhe, die es erreicht, die Kraft des Blutdrucks angiebt. </s>
            <s xml:id="echoid-s2135" xml:space="preserve">
              <lb/>
            Dies Inſtrument nennt man den Blut-Kraft-Meſſer, und es
              <lb/>
            wird gegenwärtig ſowohl für Unterſuchungen der angegebenen
              <lb/>
            Art, wie beſonders bei Verſuchen über die Wirkung gewiſſer
              <lb/>
            Medikamente benutzt, deren Einfluß auf die Kraſt des Herzens
              <lb/>
            man prüfen will. </s>
            <s xml:id="echoid-s2136" xml:space="preserve">Es verſteht ſich von ſelbſt, daß man bei
              <lb/>
            Verſuchen dieſer Art zu Tieren ſeine Zuflucht nimmt.</s>
            <s xml:id="echoid-s2137" xml:space="preserve"/>
          </p>
          <p>
            <s xml:id="echoid-s2138" xml:space="preserve">Die überraſchende Erſcheinung, die ſich hierbei heraus-
              <lb/>
            ſtellte, iſt die, daß die Druckkraft des Blutes gar nicht von der
              <lb/>
            Größe des Tieres abhängt. </s>
            <s xml:id="echoid-s2139" xml:space="preserve">Das Blut von Pferden, Ochſen,
              <lb/>
            Kälbern, Hunden, Katzen und Kaninchen zeigt eine ganz gleiche
              <lb/>
            Druckkraft. </s>
            <s xml:id="echoid-s2140" xml:space="preserve">Das heißt: </s>
            <s xml:id="echoid-s2141" xml:space="preserve">das kleine Herz eines Kaninchens
              <lb/>
            treibt das wenige Blut im Körper dieſes Tieres mit eben
              <lb/>
            ſolcher Kraft herum, wie das große Herz eines Pferdes die
              <lb/>
            Maſſe des Pferdeblutes herumtreibt. </s>
            <s xml:id="echoid-s2142" xml:space="preserve">Man muß ſich hierbei
              <lb/>
            nicht vorſtellen, daß ein Kaninchenherz ſo ſtark iſt wie ein
              <lb/>
            Pferdeherz; </s>
            <s xml:id="echoid-s2143" xml:space="preserve">denn das iſt keineswegs der Fall, und kann auch
              <lb/>
            nicht der Fall ſein. </s>
            <s xml:id="echoid-s2144" xml:space="preserve">Ein Kaninchenherz iſt eine kleine Pumpe
              <lb/>
            für eine kleine Blutleitung; </s>
            <s xml:id="echoid-s2145" xml:space="preserve">ein Pferdeherz iſt eine große
              <lb/>
            Pumpe für eine große Blutleitung. </s>
            <s xml:id="echoid-s2146" xml:space="preserve">Die große Pumpe </s>
          </p>
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