This dissertation explores cultural narratives about technology in the Weimar Republic with a particular focus on tropes of the body-as-tool and the organic machine. At once the organic seat of the self and merely one instrument among others in the shaping of the natural world, the ambiguous figure of the instrumental body straddles the border between nature and technology while undermining any strong distinction between the two spheres. The technological anthropologies of Karl Marx, Ernst Kapp, and Helmut Plessner invoke radically divergent political visions from the relationship between technology, the human body, and its environment. The conflicted implications of this relationship are literalized in Alfred Döblin's emblematic novel Berge Meere und Giganten (1924), which pushes the trope of the body-as-tool to a breaking point by repeatedly and spectacularly rupturing the bounds of the body itself; this topological assault on the autonomous individual reflects the confluence of Döblin's monist philosophy of nature and his avant-garde critique of the novel form. I then analyze key contributions to Weimar-era photographic discourse by Döblin, Brecht, Benjamin, Kracauer, and Albert Renger-Patzsch to unfold the uneasy relationship between physiognomy - the belief in the body's inherent legibility - and the way photography as technology compels the visible body to speak. And for Ernst Jünger, future technology itself becomes a human organ, thereby closing the progression of human history in a static, elemental temporality. In contrast to accounts of modernity that see an encroachment of a mechanical register on the organicist discourse of the body, my dissertation shows how the tropes of the body-as-tool and the organic machine destabilize any unidirectional relationship between nature and technology. By recovering the centrality of the organic body within contemporary technological imaginaries, my project intervenes in scholarship on the culture of the Weimar Republic by contributing a more complex - and non-teleological - picture of the aesthetic, philosophical, and political stakes of the discursive entwinements of nature and technology.