Mechanism, Experiment, Disease: Marcello Malpighi and Seventeenth-Century Anatomy

Epilogue

Epilogue The notions of mechanism, experiment, and disease were central to the history of anatomy, science, philosophy, and medicine; I will now briefly reexamine them in turn. A word of caution is in order here: my work should not be seen as a history of anatomy. On the one hand, I have omitted areas—such as myology—that were central to anatomy, although not to Malpighi’s work; on the other hand, I have included topics—such as the investigation of plants and medical consultations—that would hardly figure in a history of anatomy. I hope readers found the structure I have adopted as instructive as I found it congenial. The notion of mechanism was central to anatomy in the second half of the seventeenth century: the very term “mechanism,” meaning a material mechanical device, gained common currency from Henry More’s 1659 The Immortality of the Soul. Mechanistic anatomists argued that in order to grasp how an organ works, it was necessary to understand its structure and how its components operate separately and together. Mechanisms progressively replaced the immaterial faculties of the soul, which were either dismissed altogether or, more subtly, constrained within the bounds of the body’s organs, whose structure alone offered a way to understand their operations. The challenge to the notion of faculty led anatomists to search with renewed determination how organs work in their structures and microstructures. Mechanists sought to replace notions like selective attraction and sanguification with others more amenable to their philosophy, such as filtration and fermentation. Malpighi’s mechanistic understanding of nature was tied to his belief in her regularity and uniformity regarding not just physical laws but also the actual devices she employs, which display increasing complexity from plants to lower and higher animals. Analogous mechanisms can be found in different organisms, with variations in size, structure, and mode of operation, although their purpose is unchanged: the vascular network in the lungs of frogs is not especially fine, enabling the anatomist to observe the anastomoses of arteries and veins; the optic nerve of the swordfish is so large that it 356 Mechanism, Experiment, Disease is folded like a cloth; the heart of the silkworm consists of several segments along the length of the animal, and in the late larval and subsequent stages the direction of its beat is periodically reversed. According to Malpighi, however, changes across organisms proceed continuously, step by step, without violating nature’s fundamental uniformity, because her ways of operating are the same everywhere. This conception—partly a metaphysical assumption, partly a working hypothesis that Malpighi saw confirmed in his daily investigations—played a key role in anatomical research across the dichotomy between the individual specimen under examination and the general case: the identity of nature’s laws and the analogies among her mechanisms justified Malpighi’s having recourse to the microscope of nature, mining for stones, and the microscope of disease, moving across different species, healthy and diseased states, and even jokes of nature and monsters, as he stated in De polypo cordis. It is not surprising that Malpighi saw the views of Giovanni Battista Trionfetti and Filippo Buonanni, who cautioned against hasty generalizations, as a challenge to a fundamental tenet of his worldview, destroying the true method of philosophizing by making—as he put it—everything uncertain and at the same time every bizarre thing plausible. Ultimately, however, the fortunes of mechanistic anatomy were decided on the dissecting table or under the microscope, not simply at the philosophical level. In understanding why nettles sting, how the “beards” of oats curl, or how coded arsmart discharges seeds, magnification revealed the mechanisms at play: tiny spines erupting from a sac of irritating liquid acting like a syringe, twisted components with different textures, and a coiled membrane working like a spring ready to unleash the seeds. Other processes proved more challenging. In the case of respiration, Malpighi’s 1661 findings about the microstructure of the lungs led him and Borelli to an interpretation that everyone soon found untenable. Their account was all the more surprising in view of Malpighi’s awareness that air turns blood bright red. By the end of the decade a wide consensus had been reached about respiration, accommodating Malpighi’s structural findings with striking experiments and knowledge of the chymistry of the air: Richard Lower and Robert Hooke enacted respiration in a dead animal, showing that one of the key operations associated with life involved...