with important consequences for the German Empire. By showing that diseases were caused by pathogens, which could be studied under the microscope, and not by the climatic conditions of a determined place, Koch and other bacteriologists were giving the German state the tools to expand the empire into overseas colonies. This was crucial at a time when some thinkers in the medical and anthropological fields were still stressing the inability of Germans to survive in the tropics. One of them was Rudolf Virchow, who in 1885 delivered a lecture on acclimatization at the annual Assembly of German Naturalists and Physicians (Versammlung der deutscher Naturforscher und Ärzte) in direct reaction to Bismarck’s colonial policy and against an evolutionary theory that he called the cosmopolitanism of people (Kosmopolitismus des Menschen), which was particularly popular among Dutch anthropologists.31 This view proposed that all humans shared a common origin and elementary biochemical processes that made them able to adapt to any region in the world after a period of adjustment.32 Koch and a group of young researchers who favored the expansion of the German Empire appropriated this cosmopolitan principle to assert that the best elements of Europeans could be settled in the tropics without having to perish there.33
Virchow did not believe in the quick acclimatization of any racial group migrating from one natural environment to another. In the annual assembly, he argued that northern Europeans could never adapt to African climates and defended the Lamarckian view, which stated that acquired characteristics could pass from one generation to another.34 His ideas were directed against Germany’s acquisition of overseas colonies and intended to respond to a lecture delivered earlier at the convention by August Weismann on his new theory of the continuity of the germplasm.35 Weismann’s theory proposed that reproductive cells, which he called “germ cells,” transmitted hereditary information without the influence of any somatic cells and independently from anything the body learned in the environment. According to the germplasm theory, acquired anomalies could not be transmitted to descendants when a pathological process had produced them. In Weismann’s words, “An organism cannot acquire anything unless it already possesses the predisposition to acquire it: acquired characters are therefore no more than local or sometimes general variations which arise under the stimulus provided by certain external influences.”36 However, these variations could not be transmitted from one generation to another. According to Weismann, only the predisposition could be passed down to the progeny.37 In light of this theory, diseases were not considered an intrinsic part of the human physiological development, but were viewed as “accidents” in human nature. Therefore, pathology was not considered a proper science but a study of all accidental causes acting upon human beings that changed their normal conditions in a lifetime. The only way diseases could be inherited was when they were congenital—not microbial—and directly affected the germ cells.
Virchow criticized Weismann’s position because it proposed a division between the fields of pathology and physiology when a clear line separating the functions of the two could not be established. He was skeptical of the germ theory for the same reason, and, in his opinion, “Diseases have no independent or isolated existence; they are not autonomous organisms, not beings invading a body, nor parasites growing on it; they are only the manifestations of life processes under altered conditions.”38 A disease occurred when “chemical or mechanical changes” took place in an individual’s cells. The role of pathology was to understand this structural modification of body tissues. Therefore, given this interdependency between physiology and pathology, he considered that all variations within a species, even racial ones, were pathological or a manifestation of the altered condition.39 He claimed that variations at first looked accidental, but they became the norm through inheritance. Virchow dismissed any explanation concerning people’s descent, like the one Weismann was proposing, as highly speculative and lacking empirical evidence. He opposed Darwinism and considered human beings deeply connected to their cultural and physical environments. For him, the white race was composed of different members, the “Aryans” and “Semites” being the two most striking poles.
Contrary to what colonial propagandists were proposing about the superiority of northern Europeans in the tropics, Virchow believed that the best colonizers were Jews, who he thought could undergo acclimatization more easily than the so-called Aryans, given their long history of migration and colonization. According to him, the Phoenicians were the first colonizers they knew of and were Semites who had colonized a great part of southern Europe.40 Among the Aryans, he identified those living in southern Europe as having greater potential to adapt to warm countries, not necessarily because of their proximity to the tropics, but because of their racial mixture with Semitic elements. When comparing the colonizing projects and the settlement of Europeans in the Antilles, Virchow established that the Spaniards had been more successful than their French and British counterparts in the region. This success was to be correlated with the level of racial assimilation these people had with Jews, since experience had shown that Jews were best suited to migrate to foreign lands and form permanent colonies.41 In the realm of German overseas expansion, Virchow believed that racially pure Aryans were weak and vulnerable for the tropics, and there were only few temperate zones in the world where they could be settled at the end of the nineteenth century. The tropics and subtropics were useful for Germans mainly as research stations where the study of many dangerous diseases could be undertaken.42 Virchow considered that, before sending people to die abroad, the conditions and options for acclimatization needed to be further investigated.
Considering this gloomy picture that Virchow and other medical anthropologists were painting for ethnic Germans, and given the population growth the empire was experiencing at the time, it is not difficult to understand why the state decided to embrace instead the work that came from experimental biology and bacteriology. These disciplines provided the solution for the settlement of Germans and the expansion of the German nation in warm climates. While Virchow believed that racial miscegenation was the only solution for the survival of northern Europeans in tropical colonies, Weismann gave the answer that people could survive in the tropics without transforming their racial constitution. Around the same time that evolutionary theorists were arguing that the environment did not determine people’s race and that Aryans had the power to overtake nature, Koch and other physicians were proposing that infectious diseases were caused by microorganisms that could travel anywhere according to epidemiological evidence. This biological proximity between the “cosmopolitanism” of human beings and bacteria and the tensions between race and space redefined in important ways the cultural and political relations among Germans, nonethnic Germans, and subjects in the tropical world. The main question at stake in discussions about diseases and acclimatization was, of course, racial degeneration. In Virchow’s work, the environment, by way of diseases, had the potential to degenerate an imagined “pure” German race, and only racially mixed people could resist such degeneration in the colonies. In Weismann’s theory, it was precisely miscegenation that produced racial degeneration. Yet, even Virchow’s idea of miscegenation could be viewed as racist because his anticolonial stance was based on the premise that northern Europeans should not be settled in overseas colonies due to racial degeneration.
Both the germ theory of disease and the germplasm theory of inheritance helped eliminate two significant fears people had about overseas expansion. One was the belief that diseases in the tropics were undefeatable and the other was the notion that Germans could “go native” in overseas colonies. With appropriate measures to control both miscegenation and infectious diseases, Germans could be settled in overseas colonies without having to give up their Germanness. In addition, the theories brought important transformations in the practice of colonialism, in the way physicians interacted with patients, and in the mode in which individuals related to the state. For colonialism, the introduction and institutionalization of these two theories meant that the colonial state began to rely more on experimental science and medical expertise, replacing the local knowledge provided by indigenous populations, on which earlier forms of European colonial expansion depended so much.43 Relations between doctors and patients in Germany were also affected in the sense that the knowledge obtained in the laboratory took priority over patients’ own descriptions of the condition. The theories also gave power to states to introduce regulations that controlled individuals’
