The Argentine scientist and writer Eduardo Ladislao Holmberg (1852-1937) is a pioneer in different narrative genres, particularly fantastic stories, police stories, scientific fantasy and science fiction. This article analyzes how he renews the poetics of the novel in a process ending with La bolsa de huesos (1896). His novelty lies in enhancing the creative function of fantasy in structuring novel discourse, thus maximizing fiction as a substantive element of the novel. This contrasts with romantic and naturalistic tendencies which prioritized what was morally credible (the novel as a mirror of society).