Another point of interest is the weight he attached in 1842-4 to "sports" or what are now called "mutations." This is I think more prominent in the _Foundations_ than in the first edition of the _Origin_, and certainly than in the fifth and sixth editions. Among other interesting points may be mentioned the "good effects of crossing" being "possibly analogous to good effects of change in condition,"--a principle which he upheld on experimental grounds in his _Cross and Self-Fertilisation_ in 1876. In conclusion, I desire to express my thanks to Mr Wallace for a footnote he was good enough to supply: and to Professor Bateson, Sir W. Thiselton-Dyer, Dr Gadow, Professor Judd, Dr Marr, Col. Prain and Dr Stapf for information on various points. I am also indebted to Mr Rutherford, of the University Library, for his careful copy of the manuscript of 1842. CAMBRIDGE, _June 9, 1909._ EXPLANATION OF SIGNS, &c. [] Means that the words so enclosed are erased in the original MS. <> Indicates an insertion by the Editor. _Origin_, Ed. vi. refers to the Popular Edition. PART I. Sec. I. <ON VARIATION UNDER DOMESTICATION, AND ON THE PRINCIPLES OF SELECTION.> An individual organism placed under new conditions [often] sometimes varies in a small degree and in very trifling respects such as stature, fatness, sometimes colour, health, habits in animals and probably disposition. Also habits of life develope certain parts. Disuse atrophies. [Most of these slight variations tend to become hereditary.] When the individual is multiplied for long periods by buds the variation is yet small, though greater and occasionally a single bud or individual departs widely from its type (example){36} and continues steadily to propagate, by buds, such new kind. {36} Evidently a memorandum that an example should be given. When the organism is bred for several generations under new or varying conditions, the variation is greater in amount and endless in kind [especially{37} holds good when individuals have long been exposed to new conditions]. The nature of the external conditions tends to effect some definite change in all or greater part of offspring,--little food, small size--certain foods harmless &c. &c. organs affected and diseases--extent unknown. A certain degree of variation (Mueller's twins){38} seems inevitable effect of process of reproduction. But more important is that simple <?> generation, especially under new conditions [when no crossing] <causes> infinite variation and not direct effect of external conditions, but only in as much as it affects the reproductive functions{39}. There seems to be no part (_beau ideal_ of liver){40} of body, internal or external, or mind or habits, or instincts which does not vary in some small degree and [often] some <?> to a great amount.