For a very little reflection will show that identity, as commonly predicated of living agents, does not consist in identity of matter, of which there is no same particle in the infant, we will say, and the octogenarian into whom he has developed. Nor, again, does it depend upon sameness of form or fashion; for personality is felt to survive frequent and radical modification of structure, as in the case of caterpillars and other insects. Mr. Darwin, quoting from Professor Owen, tells us (Plants and Animals under Domestication, vol. ii. p. 362, ed. 1875), that in the case of what is called metagenetic development, “the new parts are not moulded upon the inner surfaces of the old ones. The plastic force has changed its mode of operation. _The outer case_, _and all that gave form and character to the precedent individual_, _perish_, _and are cast off_; _they are not changed_ into the corresponding parts of the same individual. These are due to a new and distinct developmental process.” Assuredly, there is more birth and death in the world than is dreamt of by the greater part of us; but it is so masked, and on the whole, so little to our purpose, that we fail to see it. Yet radical and sweeping as the changes of organism above described must be, we do not feel them to be more a bar to personal identity than the considerable changes which take place in the structure of our own bodies between youth and old age. Perhaps the most striking illustration of this is to be found in the case of some Echinoderms, concerning which Mr. Darwin tells us, that “the animal in the second stage of development is formed almost like a bud within the animal of the first stage, the latter being then cast off like an old vestment, yet sometimes maintaining for a short period an independent vitality” (“Plants and Animals under Domestication,” vol. ii. p. 362, ed. 1875).