Background

Émile Duclaux was born on June 24, 1840 in Aurillac, France. He was the son of Justin Pierre Duclaux and Agnès Duclaux. His father was bailiff of the court at Aurillac, where his mother ran a small grocery. As a child, his long walks through the beautiful Auvergne countryside gave Duclaux a taste for nature and poetry; and his parents’ example revealed to him the value of sincerity, simplicity, and perseverance.

Education

In 1857, upon completing his classical education at the local collège, Duclaux left Aurillac and went to Paris to attend the special mathematics course at the Lycée Saint-Louis. Two years later he was accepted at both the École Polytechnique and the École Normale Supérieure; he chose the latter. In 1862 he became agrégé in the physical sciences.

He defended his doctoral thesis in physical sciences in 1865.

Career

Duclaux was retained by Pasteur as his laboratory assistant at the École Normale Supérieure. It was during this period that the discussions of the possibility or impossibility of spontaneous generation were at their liveliest. Pasteur maintained that the microscopic creatures responsible for fermentation came from parents similar to themselves. Nicolas Joly, Pouchet, and Musset asserted that, on the contrary, these creatures were born spontaneously in organic fluids. From time to time Dumas and Balard, members of the commission named by the Académie des Sciences to settle the question, came to the École Normale. Duclaux, who had already participated in the experiments of his mentor, now attended the debates. The impression they made on him showed him his true course in life.

Dissociated from Pasteur’s laboratory, Duclaux faced an uncertain future. In 1865 Duclaux decided to leave Paris. He became a teacher first at the lycée in Tours, then at the Faculty of Sciences at Clermont-Ferrand, in which city his mother, a widow since 1860, joined him. He was able to renew his collaboration with Pasteur, first at Pont-Gisquet, Gard, where the master was pursuing his work on silkworm diseases, and a little later at Clermont-Ferrand. The experiments on fermentation began in a makeshift laboratory set up by Duclaux and were repeated on a much greater scale at the Kuhn brewery in Chamalières, which is between Clermont-Ferrand and Royat. It is well known that these experiments were requested in order to revive the brewing industry.

New professional duties brought Duclaux to Lyons in 1873 and finally to Paris in 1878. In Paris, he won a competition for the professorship of meteorology at the Institut Agronomique, and he was also given a lectureship in biological chemistry at the Sorbonne. He immediately used this opportunity to give a course in microbiology, the first of its kind anywhere.

After his wife's death, Duclaux threw himself into his work with even greater energy in order to forget his grief. He taught, experimented, and wrote; and he followed, day after day, Pasteur’s extraordinary series of accomplishments. These included the development of vaccines against fowl cholera, anthrax, swine fever, and, in 1885, against rabies. In 1888 the Institut Pasteur was founded in Paris on rue Dutot. Duclaux, who meanwhile had become a titular professor at the Sorbonne, transferred his teaching activities to the Institut Pasteur. A little earlier, through his efforts a new monthly journal, the Annales de l’Institut Pasteur, was created to publish research in microbiology.

Beginning with this period, one may say that Duclaux’s life was almost inseparable from that of the Institut Pasteur. At the death of its brilliant founder in 1895, he took over its direction and in a few years made it into a sort of “scientific cooperative,” in which each scientist, while preserving the independence of his own ideas, worked toward a common goal. To the original buildings were added, at the beginning of the century, the Institut de Chimie Biologique and a hospital.

In January 1902 he suffered his first stroke. Scarcely recovered, he began to write again for the Annales and in the spring of 1903 recommenced his lectures. But this was too much to demand of an overtaxed body. On the evening of May 2, 1904, Duclaux suddenly lost consciousness and died in the night. His place as director of the Institut Pasteur was assumed by one of his pupils from Clermont-Ferrand, Émile Roux.

Duclaux’s scientific work is at once that of a physicist and that of a chemist. As a physicist, he studied the phenomena of osmosis, of molecular adhesion, and of surface tension. As a chemist, he concentrated especially on fermentation processes. In this area he was to some extent following up the work of Pasteur. As the years passed he was led to accord to enzymes (then called diastases) an increasingly important role in the phenomena of life.

He devoted a long series of investigations to the respective roles played in the intestinal tract of men and animals by enzymes issuing from glands and by those liberated by microbes. He recognized that the microbes had no role in gastric and pancreatic digestion, which involve only juices released from the tissues. Microbial digestion does not begin until the intestine, but then rapidly becomes important. In a related area, Duclaux realized that microbes are indispensable in the formation in the soil of plant nutrients. Without microbes, the earth is infertile, because the enzymes in the plant cells cannot leave the cells and thus cannot act outside the plant.

Milk provided Duclaux with a material ideally suited to the study of enzymes. In the first stage, through a great number of analyses, he was able to develop methods permitting the determination of the proportions of its constituents. In the second stage he studied the enzymes capable of modifying the constituents.

The great importance of enzymes was shown in the transformation of milk into cheese. In this case, however, the active agents are of external origin. A cheese is, in fact, the result of microbial cooperation: “Each of the microscopic workers must act in its turn and stop at the right moment. Such a workshop is difficult to direct, and one may say that it has required the experience of centuries to obtain products whose taste and appearance are always the same.”

Duclaux studied several types of cheese, but undoubtedly with particular relish the cheese from Cantal, one of the riches of his native area.

Achievements

• Émile Duclaux is remembered as a prolific scientist who, with Pasteur, made significant contribution to the study of silkworm diseases, and also took part in experiments to debunk the theory of spontaneous generation. He also undertook studies of phylloxera, an aphid-like pest that plagued grape vineyards, performed research on the composition of milk, and conducted studies on beer and wine.
  
  He initiated the custom of naming enzymes by adding the suffix "-ase" to the enzyme's substrate.
  
  Duclaux was also a prolific writer; some of his better known publications were "Traité de microbiologie," "Ferments et maladies" and "Pasteur, histoire d'un esprit," the latter being a biography dedicated to Pasteur.
  
  He was awarded the Order of the Legion of Honour.

Works

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  • Pasteur 1896
  • Traité De Microbiologie 1897
  • L'Hygiène Sociale 1902
  • Le Lait 1887
  • Ferments Et Maladies 1882
  • Atmospheric actinometry and actinic constitution of the atmosphere 1896
  • Le Microbe Et La Maladie 1886
  • Avant Le Proces 1898
  • Cours De Physique Et De Meteorologie 1891
  • Propos d'Un Solitaire 1898
  • Propos d'Un Solitaire 1899

Politics

On several occasions Duclaux's devotion to the truth led him to enter into political conflicts. In particular, he was a vocal supporter of Alfred Dreyfus when he was unjustly accused of treason.

Views

Duclaux belonged to that group of physicists and chemists, still limited in the second half of the nineteenth century, who through their work increased our knowledge of living matter. He was one of the first to believe in microbes, and the books he devoted to them have long remained the “gospel” of the new doctrine.

He dreamed of a universal brotherhood under the banner of science - “the common fatherland,” as he used to say, “where one could have passions without having hatreds.” But he was not oblivious to what was happening outside his laboratory.

Membership

Duclaux became a member of the Académie des Sciences in 1888, of the Société Nationale d’Agriculture in 1890, and of the Académie de Médecine in 1894.

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  Académie des Sciences , France

  1888

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  Société Nationale d’Agriculture , France

  1890

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  Académie de Médecine , France

  1894

Personality

Duclaux the teacher was no less remarkable than Duclaux the researcher. He was captivating, full of wit and verve. He was also a just man with a passionate soul.

Quotes from others about the person

• Émile Roux wrote: “Duclaux presented a subject so clearly that everyone understood. His words were those of a scientist burning with the sacred fire. He set thinking to the point that when one had finished his course, he seemed to be there still.”
  
  Émile Roux also wrote: “Duclaux's works display the logic of the scientist and the style of the poet. He could extract from a memoir possible consequences that the author himself had not always suspected. How many ideas he explored; what new insights he lavishly bestowed. Duclaux sowed the high wind.”

Connections

Duclaux was married to Mathilde Briot. She was quite young when she succumbed suddenly to puerperal fever following the birth of their second son.

In 1901 he married Agnes Mary Frances Robinson, a well-known author.

His son, Jacques Eugène Duclaux, was a highly regarded chemist.

Father:

Justin Pierre Duclaux

Mother:

Agnès Duclaux

Spouse:

Agnes Mary Frances Robinson

late spouse:

Mathilde Briot

Son:

Jacques Eugène Duclaux

colleague:

Louis Pasteur

Student:

Pierre Paul Émile Roux

References

• Annales De L'institut Pasteur, Volume 18
  1904