 The second claim, essentialism about kinds, does not obviously imply the first, individual essentialism. To see this, consider the following two cases that would seem to show that the latter does not imply the former (Bird 2018). The first case is chemical/physical. A nucleus of neptunium-239 may undergo beta decay, in which one of its neutrons emits an electron leaving a proton. As a consequence the nucleus now has one more proton and so is a nucleus of neptunium no longer but is now a nucleus of plutonium. This description is consistent with the claim that it is essential to neptunium that nuclei of neptunium atoms have 93 protons whereas it is essential to plutonium that its nuclei have 94 protons. But one may also claim, as the description implicitly suggests, that one and the same nucleus persists through this transformation. If that is so, then a particular has retained its identity while undergoing a change of kind. That kind essentialism does not entail essentialism of kind membership is also demonstrated by a second, biological, example. According to Mayr’s biological species concept, a species is a reproductively isolated breeding population. Thus a new species can be created by the advent of reproductive isolation, which will typically split existing populations (Matthen 2009). And so the existing organisms in at least one (and arguably both) of the newly isolated (sub-)populations will belong to a new species. And if species are natural kinds, this is an example of particulars changing their kinds. But this account of species is consistent with the view that species have essences (LaPorte 1997, 2004, 11–12). (As a matter of fact, most essentialists accept that an object’s kind is essential to it. The point being advanced here is that this claim does not follow immediately from the claim that kinds have essences.)