The inheritance of acquired characters becomes very obvious in the following example: The Monera are the lowest living organisms known; they consist of a mass of protoplasm, and are still devoid of even a nucleus. They multiply simply by division; each half is like the other, and like the parent (which by this process has ceased to exist), except that each is smaller and has to grow. A certain Moneron, _Protomyxa aurantiaca_, is orange-coloured, and its offspring is from the beginning of the same colour, and this colour has been acquired by that kind of Monera-like protoplasm which thereby has become the species called Aurantiaca. We have no reason for assuming that there existed from the beginning of life not only colourless, but also red, orange, and other kinds of protoplasm. In these simplest of organisms the whole process of heredity seems very obvious; but in the higher ones, in those which propagate by eggs, the problem is infinitely more complicated. It is true that the egg is, strictly, nothing but a small part of the parental organism, and we know from everyday experience that this single egg-cell has in it all the attributes and characteristics of the parent; but these attributes and characteristics make their appearance successively, just as the egg cell of a chick has neither wings nor feathers, not even a backbone, but develops these organs because its parents have them. The theory that acquired characters are hereditary has often been vigorously attacked; but the champions of the negative position have not given us anything satisfactory instead. They question, also, the principle of adaptation as a factor in Evolution, and substitute 'variation,' coupled with 'natural selection.' They point to Darwin's argument: (1) It is a fact that animals and plants produce a much greater number of young than in their turn grow up to propagate the race; (2) no two of the frequently many individuals of the same breed are exactly alike, although the differences may be hidden to our perception (this is quite true, because no two entities can live in absolutely the same place and conditions); (3) through heredity the offspring takes over the faculties and features of the parents; (4) what decides which of the many individuals (each one possessing some aberration or variation) are to live and to propagate the race?--obviously those individual variations which happen to make the lucky possessors most fit for the struggle for life.