The Song of the Cell: An Exploration of Medicine and the New Human

In the mid-1800s, two camps divided the world of medicine: pathology and anatomy. Anatomy was more advanced at this time compared to pathology. Mukherjee notes that after the 16th century, “anatomists began to describe the forms and structures of the human body with increasing precision” (19). However, they still relied on outdated and often incorrect anatomical teachings from the Roman era. Andreas Vesalius, one of the most well-known anatomists of the 1500s, helped revolutionize the field of anatomy through his intricate drawings of the human body.

In contrast to anatomy, pathology, or the study of human diseases and their causes, was an underdeveloped field. Prior to the 18th century, people believed that miasmas, or “poisonous vapors emanating from sewage or contaminated air” (22), caused disease. For this reason, health reformers focused on increasing public hygiene and reforming sanitation systems to prevent disease. While these methods helped curb some diseases, they didn’t help doctors and scientists explain human diseases in a standardized manner. As a result, most believed that “dysfunctions of an individual organ” (23) led to disease.

Rudolf Virchow, a young physician just out of medical school, was deeply unsatisfied with the state of pathology in the mid-1800s. After reviewing research by plant and animal biologists, who had noted the prevalence of cells among these living specimens, Virchow pondered whether “these cells sit at the heart of physiology and pathology […] If so, where did they come from and what did they do” (24)? Virchow was determined to answer these questions.

Mukherjee notes that “the art of seeing” (26) launched modern cell biology. Building on centuries of advances to glassblowing, Hans and Zacharias Janssen, a father and son team of opticians, invented the compound microscope. A compound microscope has two lenses, whereas a simple microscope has one. The microscope enabled scientists to “find their way into an unseen, miniature world” (27) for the first time.

Using a homemade microscope, Dutch trader Antonie van Leeuwenhoek was one of the first individuals to use a simple microscope to view previously invisible organisms in rainwater. He called these organisms animalcules and thought they were strictly single-celled organisms. In addition, he looked at his own sperm and sperm from an individual with gonorrhea under a microscope, calling what he saw under the microscope “‘living atoms’” (39).

English scientist and polymath Robert Hooke, a contemporary of van Leeuwenhoek, conducted experiments and observations on single-celled organisms using a compound microscope he built. He was among the first to draw these organisms, which he called cells, for the public. After hearing about Hooke’s discoveries, Leeuwenhoek began writing to him. While Hooke responded only occasionally, he had all of Leeuwenhoek’s letters translated and sent to the Royal Society of London.

Mukherjee ends the chapter by briefly discussing the rivalry between Hooke and English mathematician Sir Isaac Newton over who first formulated the law of gravitation. Hooke claimed that he was the first to propose this theory and that Newton plagiarized his idea. Mukherjee argues that Hooke’s claim was ridiculous. While Hooke and several colleagues observed that the sun attracted planets through “invisible ‘forces’” (36), their studies lacked the rigor of Newton’s argument. History accuses Newton of stealing Hooke’s sole portrait, although Mukherjee finds this unlikely. Regardless of whether the story is true, there are no surviving paintings of Hooke. Mukherjee notes, “The pioneer of optics, the man who brought the whole universe into view, is invisible to us” (36).

Following Hooke’s discovery of the cell wall, scientists in the late 17th and early 18th centuries focused on understanding the microscopic structure of plant and animal specimens. Scientists realized that Leeuwenhoek’s “living atoms” weren’t just single-celled organisms but that they organized themselves into tissues in more complex living beings (e.g., plants and animals).

One of the most famous scientists from this time period, François-Vincent Raspail, was especially interested in understanding the function, composition, and origin of cells. Mukherjee notes that Raspail anticipated “the idea of a selective, porous cell membrane, the autonomy of a cell, and the notion of the cell as a metabolic unit” (40). In addition, Raspail theorized that tissues and organs stem from chemical processes controlled by cells, and he suggested that “‘from cells come cells’” (40), or Omnis cellula e cellula in Latin. Because of the infancy of tools and experiments during this time, Raspail was unable to deeply investigate his theories. Regardless, he radically changed the “conception of what a cell is and does” (40).

Raspail’s findings went unnoticed by the scientific community because of two scientific debates that raged during this period. Vitalism represents the first debate. This theory dates to Aristotle and purports that “living beings could not possibly be built out of the same chemicals that were pervasive in the natural world” (41). Vitalists believed that living beings contained fluid, or a divine mark or spirit, that separated them from nonliving beings—and that a divine being, or Creator, made living beings from cells. The origin of cells concerned vitalists. There were several theories, including “that cells were born within cells, like humans inside human wombs” (42) or “the cells ‘crystallized’ spontaneously out of vital fluid, like chemicals crystallizing in the inorganic world” (42). Non-vitalists, in contrast, believed the opposite. The second debate concerned preformation, or the theory that humans and other living organisms develop from miniature versions of themselves in the womb. Scientists who held this belief couldn’t comprehend how humans, who are exceedingly complex beings, formed in the womb without this preform template present in the fertilized egg. To become an established field, cell theory needed to demolish both vitalism and preformation.

The demolition of preformation and vitalism began with the findings of Schwann and Schleiden. The two collaborators argued that cells are the building blocks in all living organisms. Despite this revolutionary idea, however, the two scientists couldn’t determine the origin of cells.

Mukherjee next returns to Rudolf Virchow. After examining the blood of a patient with elevated white blood cell levels, he coined the term “leukemia.” Virchow’s fascination with the origin of cells continued. Mukherjee notes that Virchow “could not imagine tens of millions of white blood cells developing out of nothing and for no reason” (47). Combining his macroscopic and political observations, he began to ponder if these abnormal cells came from other normal cells.

Mukherjee ends the chapter by discussing one of his own medical cases, which helped him understand the importance of cells in identifying and treating diseases.

Mukherjee begins this chapter by explaining germ theory—the idea that “microbes are independent, living cells capable, in some cases, of causing human illnesses—that would first bring the cell (in this case, the microbial cell) into intimate contact with pathology and medicine” (56). While germ theory was in its infancy in the 18th century, it led scientists to ponder the relationship between microbial cells and infection.

Scientists began to make the connection between human disease and microbial cells while examining what causes rot. The origins of rot interested not only scientists but also theologians in the 19th century. Some Christian doctrines purported that the bodies of saints and kings were spared rot while they waited to ascend to heaven. However, this belief didn’t match the reality on the ground, leading to a religious reckoning.

French chemist and microbiologist Louis Pasteur investigated the origin of rot and uncovered two key findings. The first was that bacterial cells caused rot. The second was that microbes, or single-celled organisms, caused infections.

Building on Pasteur’s work, German physician Robert Koch postulated four tenets for the cause of infection based on experiments with anthrax. These tenets are:

(1) the organism/microbial cell must be found in a diseased individual, not in a healthy individual; (2) the microbial cell must be isolated and cultured from the diseased individual; (3) the inoculation of a healthy individual with a cultured microbe must recapitulate the essential features of the disease; and (4) the microbe must be re-isolated from the inoculated individual and match the original microorganism (59).

Koch and Pasteur’s work was groundbreaking but didn’t explain the connection between rot caused by microbial cells and infections in humans. Ignaz Semmelweis, a Hungarian obstetrician, was the first to start explaining this relationship. He worked at a Viennese maternity hospital, which had two wards for childbirth. One of the wards, which was managed by surgeons and students who also worked in the pathology department, had much higher maternal and infant mortality rates than the other, which was run by midwives. Semmelweis believed that the doctors and students introduced microbes into the maternity ward environment. After students and doctors were encouraged to wash their hands before entering the clinic, maternity and infant mortality rates plummeted. Unfortunately, contemporary scientists dismissed Semmelweis as a crackpot.

Mukherjee turns next to English physician John Snow. Through his studies of cholera outbreaks, he showed that germs, cells, and risk all played a role in human disease. This discovery united the fields of epidemiology, germ theory, and cell theory. Mukherjee notes that even today he still remembers “Germs. Cells. Risk.” (66) when he comes across an undiagnosable illness.

Germ theory was transformational for the field of medicine. Surgery was incredibly unsanitary. This changed, however, with Joseph Lister, a young surgeon. He was the first to boil his tools in carbolic acid, which killed the germs that caused infections. Like Semmelweis’s theory, Lister’s theory wasn’t initially accepted by his contemporaries.

The invention of antibiotic drugs in 1910 by Drs. Paul Ehrlich and Sahachiro Hata “changed the face of medicine” (67). Antibiotics recognize human cells. This enables them to distinguish between human and bacterial cells and attack only the latter.