[Embryology, 'chemical geography' of the cell and synthesis between morphology and chemistry (1930-1950)]. / L'embryologie, la 'géographie chimique' de la cellule et la synthèse entre morphologie et chimie (1930-1950).

Chemical embryology was born in 1931 with the publication of Chemical Embryology by Joseph Needham. In the following two decades it became an innovative research project aiming at the description of the construction of the embryological structure and differentiation in biochemical terms. This research programme produced a vast amount of experimental evidence and theories on the chemical dynamics of the embryo: particularly chemical characterization of the zygote and the developing embryo, the chemical exchanges between the nucleus and the cytoplasm, the significance of subcellular structures, and the role and distribution of nucleic acids within the cell. From the 1950s on, a large part of these results came to be integrated into the empirical basis of molecular biology. However, the shift from chemical embryology to molecular embryology was not just a semantic shift but a deep theoretical change, produced by the introduction of a new model of scientific explanation, based on the transmission and expression of genetic information and opposed to the biochemical definition of life.

The concept of specificity and the Italian contribution to the discovery of the malaria transmission cycle.

At the dawn of the 20th century, the change in the scientific, political and cultural attitudes towards malaria was the result of the discovery of the theoretical simplicity of the malaria transmission cycle and of the possibility to interrupt it, by avoiding the contacts between people and mosquitoes. The 'mosquito hypothesis', suggested already in the 1880s, had to be included into a coherent scientific theory, in which a fundamental part was played by the concept of specificity. The paper analyses the Italian contribution to this scientific change and the epistemological aspects of the debate between Ronald Ross and Battista Grassi about their respective role in the discovery of the human malaria transmission cycle. This debate has been often interpreted in sociological or psychological terms. However, behind the dispute there is a different definition of what is a scientific explanation in biological sciences and in particular in parasitology. This point is made clear by the analysis of four different theoretical problems implied in the discovery of the transmission cycle: the concept of specificity, the comparative method in parasitology, the specificity of the life-cycle of parasites and vectors, and the role of the analogical reasoning in science and medicine.

Unum facere et alterum non omittere: antimalarial strategies in Italy, 1880-1930.

At the end of the XIXth Century the attitude towards malaria changed dramatically from fatalism and resignation to an active policy that made the eradication of the disease a possible objective. This dramatic change in the scientific political and cultural attitudes towards malaria was the result of two main phenomena: i) the impact of the scientific medicine and Pasteurian revolution on medicine and health policies, and ii) the discovery of the theoretical simplicity of the cycle of malaria transmission and of the possibility to interrupt it, by avoiding the contacts between people and the Anopheles mosquitoes. However, scientifically based strategies against malaria were in place before the discovery of the real causative agents and of the transmission cycle at the end of the XIXth century, as the origin of the scientific medicine had already produced a 'rationale' for local and national campaigns against malaria. According to Tommasi-Crudeli, for example, the cause of malaria was not a 'chemical compound', a 'miasma', but a 'living ferment', specific and autonomous. As a consequence, the aim of antimalarial measures was to eliminate the conditions indispensable to the multiplication of the specific ferment contained in the soil. The theory of malaria aetiology changed after the discovery of the transmission cycle by Ross and Grassi, but the general strategy remained the same: to eliminate one of the factors indispensable to the multiplication and diffusion of the agent. The detailed knowledge of the malaria transmission cycle made it possible to define the exact conditions which were alone responsible for the propagation of the disease and its persistence in the endemic areas. The theoretical linearity and the specificity of the 'Grassi's law' was decisive and produced a fundamental paradigmatic shift in the antimalarial policies. The essential point for the epidemiology and prophylaxis of malaria became to clarify the conditions which contribute to facilitate or to prevent the infection of the Anopheles.

Molecular diseases and diseased molecules: ontological and epistemological dimensions.

In 1949, Linus Pauling and collaborators published in Science a paper provocatively titled: 'Sickle cell anemia, a molecular disease'. What was actually meant by 'molecular disease'? We interpret the concept of molecular disease in the frame of the traditional positions about the nature of diseases, the ontological and the physiological positions. We conclude that the physiological does not give an adequate account of what molecular diseases are. The ontological position, when correctly reinterpreted, leads to an understanding of molecular diseases where the macromolecule is seen as a symptom or as a part of a mechanism leading to the symptoms of the disease. We then show that the concept of molecular disease leads to a particular view of therapy, emphasizing eugenics as a way of eliminating disease. On the individual level, this concept leads to an increased power of diagnosis, and especially predictive diagnosis, but has little therapeutic consequence. Lastly, we examine how this concept of disease unifies two contemporary classifications of diseases, one based on the location of the diseases, the other on the cause of the diseases.

[Iatrophics and iatrochemistry: physica, chemistry and models of living organization]. / Iatrofisica e iatrochimica: la fisica, la chimica ed i modelli dell'organizzazione del vivente.

Medical secularization which develops in Europe since XVIth century allows the human body to be considered as an autonomous physical being. Consequently, medicine tries to explain illness and health through the general rules of mechanics and chemistry. The development of medical systems - seen in terms of the two leading theories of iatrochemistry and iatrophysics, was centered around the problem of control in living objects, whose analysis is still useful in the present debate. Past and present are linked by a common effort towards the explanation of life phenomena, health and illness - despite the obvious methodological gaps of the different cultural periods.

Anophelism without malaria: an ecological and epidemiological puzzle.

Since 1898, when it was established that malaria was transmitted by the Anopheles, the theory has had many sceptics and critics. One of the most serious objections was that Anopheles mosquitoes existed in regions which were not malarious, although they could have been, given the climatic and ecological conditions ('anophelism without malaria'). The history of this epidemiological problem passed through four different phases. In the first, it simply did not exist, because before Ross and Grassi's discoveries one can observe the presence of the Anopheles mosquitoes and the absence of malaria without considering it surprising. In the second phase it became a possible refutation of the mosquito theory of malaria transmission. In the third, after the definitive acceptance of this theory, anophelism without malaria was considered as a puzzle, a paradox, an enigma to be solved. Finally, in the fourth phase, after the discovery of the maculipennis subspecies complex, it became the aim of the antimalarial activities. The historical analysis of this epidemiological problem suggests many insights on the delicate and always changing malaria ecosystem.

[Not Available]. / [The organism as a chemical labaoratory: organic chemistry and medical systems in the first half of XIXth century]

The chemical revolution which arose between XVIIIth and XIXth centuries, had a special influence on the studies about living organisms and medicine. The idea was that the laboratory's discoveries could be applied to all the chemical transformation occurring in the human body. This point of view allowed the development of exerimental physiology and led to the birth of physiological chemistry; it influenced also a new theoretical discussion in medicine, by suggesting possible application to diagnostic and therapy. Paradoxically, in consideration of the importance of iatrochemistry in last centuries, the chemical revolution had a really small influence on medical systems.

[The discovery of transmission mechanisms and the fight against malaria in Italy]. / La scoperta dei meccanismi di trasmissione e la lotta contro la malaria in Italia.

The Italian experience on the eradication of malaria is particularly significant, owing to the high endemicity of malaria in a large part of the territory of the newly formed Kingdom of Italy, the scientific level of the Italian research centres and medical structures, the efficacy of the legislative and institutional developments, the part played by the Italian School of Malariology (Bastianelli, Bignami, Celli, Fermi, Golgi, Grassi, Marchiafava, Missiroli, Raffaele) in the discovery of the transmission mechanisms and in the clarification of the ecology and epidemiology of malaria. A global approach, which combines the different antimalarial measures with the bettering of the sanitary structure and a constant activity of a high level of scientific and medical research is the key to understand the reason of the success of the antimalarial campaigns in Italy.

[International health organizations facing the emergence of new infectious diseases]. / Les organisations sanitaires internationales face à l'émergence de maladies infectieuses nouvelles.

Throughout history, international health collaboration gradually came into being to counteract the emergence of new diseases. This process went through five stages.: 1) Quarantine regulations were established for maritime commerce to safeguard public health. 2) Scientific data were studied to understand the causes of infectious diseases and their modes of transmission; a single solution to the problem was not sufficient because of the diversities of the various factors triggering these diseases. Furthermore, defensive and protective measures adopted in Europe were inadequate after the colonial expansion of European countries. 3) If 19th century international health politics were defensive, the aim in the 20th century was to fight infectious diseases and to eradicate them. This third phase saw the rise of international institutions. These agencies aimed at favouring better health organization in individual countries. 4) The World Health Organization was founded, the aim being to fight existing epidemics, little importance being given to 'emerging diseases'. 5) A series of new infectious diseases and the reemergence of old diseases (a consequence of major ecological changes) that were thought to be eradicated revealed the need for continuous surveillance.

[The bacteriological revolution and theories of the etiology of goiter and cretinism]. / La révolution pastorienne et les théories sur l'étiologie du goitre et du crétinisme.

During the 19th century, a large number of researchers produced many different and even contradictory theories about the aetiology of endemic goiter and cretinism. The bacteriological revolution, i.e. the acceptance of the germ theory of infectious diseases, pushed scientists to try to isolate a germ for every disease. In the case of goiter and cretinism, this was fruitless endeavour. Nevertheless, the impact of the bacteriological revolution was largely positive because it provided a new scientific model of the genesis of disease and strengthened confidence in the possibility of fighting endemic as well as epidemic disease by simple but generally applied preventive measures such as, in the present case, iodine prophylaxis.