One of the most puzzling conundrums in contemporary evolutionary biology concerns the ontological status of species. The debate developed gradually after the publication of Darwin ' s most famous work, The Origin of Species, and it is not restricted to taxonomy, but has profound implications for all branches of biological science and equally for our understanding of the natural world. One of the most spectacular proposals regarding this issue belongs to David Hull who argued that species are individuals, not natural kinds as they were traditionally considered. Consequently, according to Hull, individual organisms studied by naturalists are just parts of species as individual entities. Although Hull ' s definition has been praised by many philosophers of biology, it was not very well-received by biologists themselves for obvious reasons: it is profoundly counter-intuitive and doesn ' t seem to fit well with our empirical observations. In the present paper I will argue that Hull ' s idea could still be a promising hypothesis and I will try to respond to the main objections which have been formulated against it.