It may be contended, too, that while it does violence to our established way of thinking, this mode of interpreting the facts is not without its difficulties. Something seems to be gained by restricting the application of the title individual, to organisms which, being in all respects fully developed, possess the power of producing their kind after the ordinary sexual method, and denying this title to those incomplete organisms which have not this power. But the definition does not really establish this distinction for us. On the one hand, we have cases in which, as in the working bee, the whole of the germ-product is aggregated into a single organism; and yet, though an individual according to the definition, this organism has no power of reproducing its kind. On the other hand, we have cases like that of the perfect _Aphis_, where the organism is but an infinitesimal part of the germ product, and yet has that completeness required for sexual reproduction. Further, it might be urged with some show of reason, that if the conception of individuality involves the conception of completeness, then, an organism which possesses an independent power of reproducing itself, being more complete than an organism in which this power is dependent on the aid of another organism, is more individual. § 74. There is, indeed, as already implied, no definition of individuality that is unobjectionable. All we can do is to make the best practicable compromise. As applied either to an animate or an inanimate object, the word individual ordinarily connotes union among the parts of the object and separateness from other objects. This fundamental element in the conception of individuality, we cannot with propriety ignore in the biological application of the word. That which we call an individual plant or animal must, therefore, be some concrete whole and not a discrete whole. If, however, we say that each concrete living whole is to be regarded as an individual, we are still met by the question--What constitutes a concrete living whole? A young organism arising by internal or external gemmation from a parent organism, passes gradually from a state in which it is an indistinguishable part of the parent organism to a state in which it is a separate organism of like structure with the parent. At what stage does it become an individual? And if its individuality be conceded only when it completely separates from the parent, must we deny individuality to all organisms thus produced which permanently retain their connexions with their parents? Or again, what must we say of the _Hectocotylus_, which is an arm of the Cuttle-fish that undergoes a special development and then, detaching itself, lives independently for a considerable period? And what must we say of the larval nemertine worm the pilidium of which with its nervous system is left to move about awhile after the developing worm has dropped out of it?