It was a large sheet of paper, yellow with age, with folds cut by wear, on which was drawn boldly a symbolical tree, whose branches spread and subdivided into five rows of broad leaves; and each leaf bore a name, and contained, in minute handwriting, a biography, a hereditary case.
A scientist’s joy took possession of the doctor at sight of this labor of twenty years, in which the laws of heredity established by him were so clearly and so completely applied.
“Look, child! You know enough about the matter, you have copied enough of my notes to understand. Is it not beautiful? A document so complete, so conclusive, in which there is not a gap? It is like an experiment made in the laboratory, a problem stated and solved on the blackboard. You see below, the trunk, the common stock, Aunt Dide; then the three branches issuing from it, the legitimate branch, Pierre Rougon, and the two illegitimate branches, Ursule Macquart and Antoine Macquart; then, new branches arise, and ramify, on one side, Maxime, Clotilde, and Victor, the three children of Saccard, and Angelique, the daughter of Sidonie Rougon; on the other, Pauline, the daughter of Lisa Macquart, and Claude, Jacques, Étienne, and Anna, the four children of Gervaise, her sister; there, at the extremity, is Jean, their brother, and here in the middle, you see what I call the knot, the legitimate issue and the illegitimate issue, uniting in Marthe Rougon and her cousin François Mouret, to give rise to three new branches, Octave, Serge, and Désirée Mouret; while there is also the issue of Ursule and the hatter Mouret; Silvère, whose tragic death you know; Hélène and her daughter Jean; finally, at the top are the latest offshoots, our poor Charles, your brother Maxime’s son, and two other children, who are dead, Jacques Louis, the son of Claude Lantier, and Louiset, the son of Anna Coupeau. In all five generations, a human tree which, for five springs already, five springtides of humanity, has sent forth shoots, at the impulse of the sap of eternal life.”
He became more and more animated, pointing out each case on the sheet of old yellow paper, as if it were an anatomical chart.
“And as I have already said, everything is here. You see in direct heredity, the differentiations, that of the mother, Silvère, Lisa, Désirée, Jacques, Louiset, yourself; that of the father, Sidonie, François, Gervaise, Octave, Jacques, Louis. Then there are the three cases of crossing: by conjugation, Ursule, Aristide, Anna, Victor; by dissemination, Maxime, Serge, Étienne; by fusion, Antoine, Eugène, Claude. I even noted a fourth case, a very remarkable one, an even cross, Pierre and Pauline; and varieties are established, the differentiation of the mother, for example, often accords with the physical resemblance of the father; or, it is the contrary which takes place, so that, in the crossing, the physical and mental predominance remains with one parent or the other, according to circumstances. Then here is indirect heredity, that of the collateral branches. I have but one well established example of this, the striking personal resemblance of Octave Mouret to his uncle Eugène Rougon. I have also but one example of transmission by influence, Anna, the daughter of Gervaise and Coupeau, who bore a striking resemblance, especially in her childhood, to Lantier, her mother’s first lover. But what I am very rich in is in examples of reversion to the original stock—the three finest cases, Marthe, Jeanne, and Charles, resembling Aunt Dide; the resemblance thus passing over one, two, and three generations. This is certainly exceptional, for I scarcely believe in atavism; it seems to me that the new elements brought by the partners, accidents, and the infinite variety of crossings must rapidly efface particular characteristics, so as to bring back the individual to the general type. And there remains variation—Hélène, Jean, Angelique. This is the combination, the chemical mixture in which the physical and mental characteristics of the parents are blended, without any of their traits seeming to reappear in the new being.”
There was silence for a moment. Clotilde had listened to him with profound attention, wishing to understand. And he remained absorbed in thought, his eyes still fixed on the tree, in the desire to judge his work impartially. He then continued in a low tone, as if speaking to himself:
“Yes, that is as scientific as possible. I have placed there only the members of the family, and I had to give an equal part to the partners, to the fathers and mothers come from outside, whose blood has mingled with ours, and therefore modified it. I had indeed made a mathematically exact tree, the father and the mother bequeathing themselves, by halves, to the child, from generation to generation, so that in Charles, for example, Aunt Dide’s part would have been only a twelfth—which would be absurd, since the physical resemblance is there complete. I have therefore thought it sufficient to indicate the elements come from elsewhere, taking into account marriages and the new factor which each introduced. Ah! these sciences that are yet in their infancy, in which hypothesis speaks stammeringly, and imagination rules, these are the domain of the poet as much as of the scientist. Poets go as pioneers in the advance guard, and they often discover new countries, suggesting solutions. There is there a borderland which belongs to them, between the conquered, the definitive truth, and the unknown, whence the truth of to-morrow will be torn. What an immense fresco there is to be painted, what a stupendous human tragedy, what a comedy there is to be written with heredity, which is the very genesis of families, of societies, and of the world!”
His eyes fixed on vacancy, he remained for a time lost in thought. Then, with an abrupt movement, he came back to the envelopes and, pushing the tree aside, said:
“We will take it up again presently; for, in order that you may understand now, it is necessary that events should pass in review before you, and that you should see in action all these actors ticketed here, each one summed up in a brief note. I will call for the envelopes, you will hand them to me one by one, and I will show you the papers in each, and tell you their contents, before putting it away again up there on the shelf. I will not follow the alphabetical order, but the order of events themselves. I have long wished to make this classification. Come, look for the names on the envelopes; Aunt Dide first.”
At this moment the edge of the storm which lighted up the sky caught La Souleiade slantingly, and burst over the house in a deluge of rain. But they did not even close the window. They heard neither the peals of thunder nor the ceaseless beating of the rain upon the roof. She handed him the envelope bearing the name of Aunt Dide in large characters; and he took from it papers of all sorts, notes taken by him long ago, which he proceeded to read.