This, like all other classifications of such phenomena, presents anomalies. It may be justly objected that the processes here grouped under the head agamogenesis, are the same as those before grouped under the head of discontinuous development (§ 50): thus making development and genesis partially coincident. Doubtless it seems awkward that what are from one point of view considered as structural changes are from another point of view considered as modes of multiplication.[29] There is, however, nothing for us but a choice of imperfections. We cannot by any logical dichotomies accurately express relations which, in Nature, graduate into one another insensibly. Neither the above, nor any other scheme, can do more than give an approximate idea of the truth. § 76. Genesis under every form is a process of negative or positive disintegration; and is thus essentially opposed to that process of integration which is the primary process in individual evolution. Negative disintegration occurs in those cases where, as among the compound _Hydrozoa_, there is a continuous development of new individuals by budding from the bodies of older individuals; and where the older individuals are thus prevented from growing to a greater size, or reaching a higher degree of integration. Positive disintegration occurs in those forms of agamogenesis where the production of new individuals is discontinuous, as well as in all cases of gamogenesis. The degrees of disintegration are various. At the one extreme the parent organism is completely broken up, or dissolved into new individuals; and at the other extreme each new individual forms but a small deduction from the parent organism. _Protozoa_ and _Protophyta_ show us that form of disintegration called spontaneous fission: two or more individuals being produced by the splitting-up of the original one. The _Volvox_ and the _Hydrodictyon_ are plants which, having developed broods within themselves, give them exit by bursting; and among animals the one lately referred to which arises from the _Distoma_ egg, entirely loses its individuality in the individualities of the numerous _Distoma_-larvæ with which it becomes filled. Speaking generally, the degree of disintegration becomes less marked as we approach the higher organic forms. Plants of superior types throw off from themselves, whether by gamogenesis or agamogenesis, parts that are relatively small; and among superior animals there is no case in which the parent individuality is habitually lost in the production of new individuals. To the last, however, there is of necessity a greater or less disintegration. The seeds and pollen-grains of a flowering plant are disintegrated portions of tissue; as are also the ova and spermatozoa of animals. And whether the fertilized germs carry away from their parents small or large quantities of nutriment, these quantities in all cases involve further negative or positive disintegrations of the parents.