Roubaud’s subsequent depression and moral disintegration and his wrongful conviction in the final trial leave him a pitiful and abject figure at the end of the novel. Séverine herself, despite her complicity and resolve in the attempted murder of her husband, is presented throughout the novel as a figure of innocence - timid, gentle and submissive. She longs to be once more a young girl of fifteen, to be as she was before she was abused, before her arranged marriage and before her involvement in an act of murder. Zola insists on her purity of spirit and childlike naivety. ‘Her beautiful blue eyes, so innocent and appealing ... had a permanently frightened look about them. In spite of everything, she had remained virgin’ (VI). In the end, Séverine is the unwitting victim of her own desire to repair the damage that has been done to her life. Flore, having come close to being a victim of Jacques’s murderous instinct, is, paradoxically, a victim of his rejection of her. She is also a victim of her own independent spirit; her suicide is both an act of contrition at the horror she has perpetrated and an expression of despair at ever finding happiness in a male-driven world to which she refuses to submit.

Jacques, far from being cast as the sadistic, merciless killer that might have been conjured up by contemporary accounts of ‘Jack the Ripper’, is presented as a man of an essentially gentle and innocent nature. In this he has much in common with Séverine. ‘At heart they were still children, young innocents, amazed at falling in love for the first time’ (VI). Zola’s insistence on the hereditary origin of Jacques’s affliction serves to deflect responsibility for his acts away from Jacques himself. Furthermore, Jacques’s desire to kill is presented consistently as an illness. When the mania strikes, he experiences, as described at various points in the novel, a splitting headache behind the ears, sudden fevers, blurred vision, loss of control of his limbs (especially his hands) and, it seems, contractions of the facial muscles. The attacks are accompanied by a disorientating sense of panic, a loss of memory and possibly of consciousness. He returns from his pursuit of the young lady on the train with only the vaguest recollection of where he has been or what he has done. Lombroso had suggested (wrongly) that certain types of criminal behaviour could be a consequence of epilepsy and this may have influenced Zola when he came to describe the physical symptoms of Jacques’s malady. The doctors who visit Jacques when the attacks first occur fail to diagnose the illness, and Zola gives no name to it, but it is clear that he wishes to present it as a neurological disorder. This attempted medical description of Jacques’s murderous instinct functions in two ways. It counters possible accusations of sensationalism by offering a more clinical approach to the subject and, more importantly, it points to a condition which visits Jacques and over which he has little control. Jacques’s desire to kill is not of his own volition, and he makes strenuous efforts to overcome it. He is certainly not the sort of ‘soulless’ character Zola had spoken of in connection with Thérèse Raquin. When the impulse to kill takes hold of him, it is presented as a temporary aberration, in which his naturally gentle nature and his heroic attempt to combat the enemy within are overthrown. Lombroso, having read the novel, wrote to Zola to tell him that he found such redeeming features incompatible with his own understanding of the mind of a ‘born criminal’. Jacques is presented not as an inhuman monster but as a man who is afflicted and who bravely seeks to come to terms with his affliction, a man condemned to a life of isolation and constantly forced to flee not only his potential victims but also his other self. Towards the end of the novel the future seems as bleak for Jacques as it had done for Flore. ‘All that lay before him was a night of darkness, an eternity of despair, from which there could be no escape’ (XII).6

It is not clear at what stage Zola decided that the novel would also be about railways. He had the regular opportunity of observing the workings of a busy railway station when, between 1871 and 1872, as a journalist writing for La Cloche, he travelled daily from the Gare Saint-Lazare to Versailles to report on the activities of the Constituent Assembly. In 1878 Zola bought a country house at Médan on the river Seine about thirty miles from Paris, where the railway line from the Gare Saint-Lazare ran at the bottom of the garden. He photographed the trains as they went by his house.