The First World War and its immediate consequences represented a turning point in the use of organic metaphors. While the great power of the German "people's body" had been described previously, the national state during the Weimar Republic was mainly interpreted through the categories of illness and recovery. Politicians like Theodor Lewald called for compulsory sport to be introduced as a replacement for the lost conscription in order to strengthen the body national. The statistician Friedrich Burgdörfer summarized in 1932 in his book People Without Youth the widespread concern about the "progressive aging and senescence of our body politic" in the dramatic words: "The German people driving biologically into the abyss". The Transylvanian Johann Bredt plagiarised the work with his book title People's State Research, published in 1930 in Breslau.
Body national in Nazism
In Nazi Germany, these different lines of development were combined. The "people's body" was often synonymous with the "racial" structure of a "people". In Mein Kampf, Adolf Hitler used the concept of the body national both in anti-Semitic and in racial hygiene and anti-Marxist contexts as a reference for alleged illness and poisoning. The law for the prevention of genetically ill offspring was justified with the "will of the government" to "purify the national body and gradually eradicate the pathological genetic makeup".
Population scientists like Friedrich Burgdörfer [de] understood the people's bodies during Nazism explicitly in a völkisch sense, not just as "population":
This "people" is not – like the "population" – an amorphous sum of individuals, but an organic structure, an organism. We rightly and deliberately speak of a people's body, a people's body, the cells of which are not the individual individuals in their isolation, but the families who belong to the same people in terms of blood and race as well as language, customs and culture. ... Thus the people does not just consist of the sum of the current living comrades, but everything that was, is and will be of the same blood belongs to it.
— Friedrich Burgdörfer, Demographic Statistics and Population Policy (1940)
Overall, the concept of the body national became an omnipresent metaphor during the Nazi era to describe the German population as a biological-racial unit that protects against various types of threats, or heals and cleanses those from various diseases, pests and parasites would. Thorsten Hallig, Julia Schäfer and Jörg Vögele stated that "the scientific foundations or lines of tradition and the intellectual climate within which the eugenic extermination policy of the National Socialists ... could take place were already in the political debates about the degeneration of the 'People's body' of the Weimar Republic".
Hans Asperger used the term when deporting unwanted children to the Am Spiegelgrund killing center in Vienna (after the Anschluss):
In the new Germany, we doctors have taken on a multitude of new duties in addition to our old ones. Just as the doctor often has to make painful incisions when treating the individual, we have to make incisions in the body of the people out of great responsibility. We must ensure that what is sick and what would pass this disease on to future generations, to the disaster of the individual and the people, is prevented from passing on the sick genetic make-up.
— Hans Asperger, from Herwig Czech: National Socialism and "race hygiene" in Nazi-era Vienna. In: Molecular Autism, Volume 9, 2018, pp. 29 ff.
The relationship of German population science to the racial foundation of "national body research" under National Socialism is controversial. The sociologist Carsten Klingemann [de], for example, has argued that the population scientists, who are mostly trained in sociological thinking, have always understood the "breakdown of the national body" in terms of social statistics and are less interested in the supposed homogeneity of a race than in what is called the stratification of the population in the sociological sense would. The historian Axel Flügel [de], on the other hand, has criticized such an overly "formal view" that overlooks conceptual breaks in the use of the respective vocabulary. Using the example of Gunther Ipsen's "folk history", he points out that this form of population research "has fallen behind the differentiated state of population science that weighs a large number of regional, social and cultural factors".