(5 Natural Selection
Decandoelle war of nature — seeing contented face of nature may be well at first doubted «we see it on borders of perpetual cold» — But considering the enormous geometrical power of increase in every organism, & in «every» country in ordinary cases must be stocked to full extent, reflection will show that this is case — Malthus «on» Man — in animals no moral ‹cheque› restrain — they breed in time of year when provisions most abundant, or seasons most favourable every country has its ‹climate› seasons — ‹oscillating›calculate Ratios.= oscillating from years of destruction.— if proof were wanted, let any singular change of climate hear^t1 how astoundingly some tribes increase «also introduced animals» this pressure is always ready «capacity of alpine plants to endure other climates» — think of endless seeds scattered abroad— a thousand wedges are being forced into the Œconomy of nature = This requires much reflection; ‹gos› study Malthus & calculate rates of increase & remember the resistance is only periodical —
The unavoidable effect of this that many of every species are ‹eithe› destroyed, either in egg, or ‹young or mature (that the former states the more › common‹)›— «Now in those organisms, every part of parent which tends to vary very slightly, slightly monstrous»^t2 in the course of a thousand generations infinitesimally small differences must inevitably tell,— when the^t3 «immeasurably» cold winter, or hot, or dry summer comes then out of the whole body of individuals of any species, if there be the smallest differences in their structure, habits, instinct, ‹senses› health, &c or will on the average tell— «& as conditions change,» a rather larger proportion will be preserved—^t4 so if the chief check to increase falls on seeds or eggs, so will in the course of 1000 generations «or ten 1000», those seeds (take one with down to fly) which fly furthest & get scattered most will ultimately rear most plants, & such small differences tend to be hereditary like shades of expression in human countenance: so if one perch fish deposits its eggs in infinitesimally different circumstances, as in shallower or deeper water &c &c so will this tell

Textual Features: rewritten in dark pencil

^t1 hear] conjectured transcription ^t2 «Now in those organisms, every part of parent which tends to vary very slightly, slightly monstrous»] point of interlineation unmarked ^t3 the] written over 'co' ^t4 will on…will be preserved—] crossed

Transcription and apparatus copyright the American Museum of Natural History