For my own part I cannot help thinking that the origin of varieties in species in a domesticated or cultivated state is in a sense pathological. Such variation doubtless occurs in nature, but not with such luxuriance. The breeds of domestic fowls differ so greatly that Bateson and others refuse to believe that they have all arisen from the single species _Gallus bankiva_. It seems to me from the evidence that there cannot be any doubt that they have so arisen. One fact that impresses my mind is that if we consider colour variations in domesticated animals, we find that a similar set of colours has arisen in the most diverse kinds of animals with sometimes certain markings or colours peculiar to one group, _e.g._ dappling in horses, wing bars in pigeons. Thus in various kinds of Mammals and Birds we have white and black, red or yellow, chocolate with various degrees of dilution, and piebald combinations. Why should forms originally so different, as the cat with its striped markings and the rabbit with no markings at all, give rise to the same colour varieties? It seems probable that the reason is that the original form had the small number of pigments which occur mixed together in very small particles, and that in the descendants the single pigments have separated out, with increase or decrease in different cases. It is true that historical evidence tends to show that the greatest variations, such as albinism in one direction or excess of pigment in the other in the Sweet Pea, were the first to arise (see Bateson, Presidential Address to British Association, Australia, 1914, Part I.), and the splitting appears often to be intentionally produced by crossing these extreme variations with the original form, but the possibility remains that the conditions of domestication, abundant food, security and reduced activity, lead to irregularity in the process of heredity. In any case the mere separation among different individuals of factors originally inherited together in one complex does not account for the origin of the complex or of the factors. This is somewhat the same idea as that of Bateson when he states that it is easy to understand the origin of a recessive character but difficult to conceive the origin of a dominant.