In parallel with his professional activities, Janet began a university course at the
Sorbonne in 1886. He became a member of the
French Entomological Society and the
French Zoological Society. First in his class, he began a thesis on ants and obtained his doctorate in natural sciences in 1900. Before the end of his studies, the
French Academy of Sciences regularly published his research in its reports and awarded him the Thore Prize in 1896. In 1899, he was elected president of the French Zoological Society. In 1900, he improved his
artificial nests and showed them at the Universal Exhibition in Paris. He attracted the interest of journalists who described the public's interest in ants. In 1909, the French Academy of Sciences awarded him the Cuvier Prize for his work in zoology.
Geology and paleontology Janet explored the
Paris Basin and especially its
chalk. At the request of
Edmond Hébert and his geology laboratory at the
École Pratique des Hautes Études, he organized a geological excursion around
Beauvais for the students of the Sorbonne University and the
MNHN. He assembled a collection of fossil and prehistoric pieces. He estimated it contained around 50,000 items. Other local
tertiary deposits are represented, such as the
Ypresian and
Lutetian from the regions of
Chaumont-en-Vexin,
Parnes,
Grignon,
Chambors, and
Mouy. The collection also included numerous
echinoderms, for which he co-wrote an article with
Lucien Cuénot. In the chalk of the Beauvais area, he discovered three new species of
belemnites. These are
Actinocamax grossouvrei,
Actinocamax toucasi, and
Actinocamax alfridi.
Entomology Janet was particularly interested in social
hymenoptera. In 1894, he observed a hornet's nest from its origin until the death of the last worker. During these 5 months of observations, he discovered the
trophallaxis of hornet larvae. He invented a vertical artificial nest that remained a tool for entomologists for a long time. This type of nest allowed him to understand how some insects live at the expense of ants. He surprised, for example, the
silverfish stealing the droplet of sugary liquid exchanged between two ants. He then performed in-depth studies on the internal anatomy of ants, where he endeavored to show their organization in
metameres. In the young ant queen, he discovered the transformation of flight muscles after she tore off her wings. He demonstrated that these muscles evolve into lipid cells, providing the necessary energy for this queen who does not feed during the long months it takes to establish her colony. In the end, 22 of the 24 notes he proposed to the French Academy of Sciences were related to social insects. He gradually sought to link ethology with insect physiology through histological sections. which has not evolved since its divergence from phyto-flagellates, is a living fossil that strongly recalls the beginnings of the animal kingdom. A few years later, a theory called orthobiontics emerged in which Janet outlined an organization plan for living beings. Ultimately based on excessive theorization that takes precedence over his observations, undermined by a text filled with complex neologisms, all translated into mathematical language, this theory remained inaccessible. It was also extremely poorly received in the
Revue générale des Sciences pures et appliquées (General Review of Pure and Applied Sciences).
Chemistry At the age of 78, Janet began to research atoms. He was interested in the properties of atoms and the organization of their nuclei. To synthesize his ideas, he reflected on a periodic classification of atomic elements. For him, their physico-chemical properties are intimately linked to their arithmetic and graphical arrangement. Moreover, the perfect regularity he observes at all levels of his table is, for Janet, proof that he has discovered the correct distribution law. In 1930, he even proposes to verify it by aligning his classification with the very recent quantum theory. In doing so, he is the first to state the rule that describes the order in which electrons fill the subshells of an atom. This rule, later rediscovered, is commonly called the
Madelung rule since 1936 among English speakers or the
Klechkowski rule (of Soviet origin in 1962 and in use in France). Confidentially, Janet's classification will remain completely ignored in France. Thanks to these astonishing spiral figures, it will reappear 40 years later among American chemists before a new eclipse. It has only been considered a valid alternative to the famous
Mendeleev's classification under the name of
Left Step Table for about a decade. Eric Scerri, an American historian (UCLA), has popularized Janet's form in magazines such as
Scientific American or
Pour la Science. He also devotes an entire chapter of his latest work to Charles Janet, whom he sees as a minor contributor in terms of fame, but major in terms of ideas.
Periodic table Janet started from the fact that the series of chemical elements is a continuous sequence, which he represented as a
helix traced on the surfaces of four nested cylinders. By various geometrical transformations he derived several striking designs, one of which is his "left-step
periodic table", in which
hydrogen and
helium are placed above
lithium and
beryllium. It was only later that he realized that his arrangement agreed perfectly with
quantum theory and the electronic structure of the atom. He placed the actinides under the lanthanides twenty years before
Glenn Seaborg, and he continued the series to
element 120. Janet's table differs from the standard table in placing the s-block elements on the right, so that the subshells of the periodic table are arranged in the order , , ,
ns, from left to right. There is then no need to interrupt the sequence or move the f block into a 'footnote'. He believed that no elements heavier than number 120 would be found, so he did not envisage a g block. In terms of atomic
quantum numbers, each row corresponds to one value of the sum where
n is the
principal quantum number and ℓ the
azimuthal quantum number. The table therefore corresponds to the
Madelung rule, which states that atomic subshells are filled in the order of increasing values of . The philosopher of chemistry
Eric Scerri has written extensively in favor of Janet's left-step periodic table, and it is being increasingly discussed as a candidate for the optimal or most fundamental form of the periodic table. Janet also envisaged an
element zero whose 'atom' would consist of two
neutrons, and he speculated that this would be the link to a mirror-image table of elements with negative atomic numbers – in effect
anti-matter. He also conceived of
heavy hydrogen (deuterium). He died just before the discovery of the neutron, the
positron and heavy hydrogen. His work was championed most notably by
Edward G. Mazurs. ==Family==