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DAR 205.5 Principle of divergence, transitional organs, instincts
NS II Principle of divergence, transitional-134 Note

Editorial symbols

Nov. 54
We include all in class, as «in» Crustaceæ, which are connected, but yet which no definition will define,— a proceeding explicable on descent.—1

Scientific Practice: theoretical statement; reasoning
Physical Characteristics: wove paper; grey
Textual Features: base text pencil
  • 1. This note may record the point where CD turned his concerted attention to the issue that had been hanging fire since the end of Notebook E in 1839, namely: formulating what became the Principle of Divergence in Natural Selection 227-50 and Origin 111-29. It is one of a substantial out pouring of notes written on a grey wove paper in October and particularly in November 1854, many of which CD dated individually. This specific note is unusual on two counts. It is one of only a few in this series that was written in pencil and it was written in what, for Darwin, was an unusually jumpy handwriting. Compare the hand in this note (DAR 205.5: 148) with CD's steady hand in DAR 205.5: 149. Also compare the jumpy pencil writing in DAR 205.5: 148 with a typical pencil annotation in DAR 205.5: 147. What then made CD's hand jump as he wrote this note? In his Autobiography 68-9, he wrote:

    But at that time I overlooked one problem of great importance; and it is astonishing to me, except on the principle of Columbus and his egg, how I could have overlooked it and its solution. This problem is the tendency in organic beings descended from the same stock to diverge in character as they become modified. That they have diverged greatly is obvious from the manner in which species of all kinds can be classed under genera, genera under families, families under sub-orders and so forth; and I can remember the very spot in the road, whilst in my carriage, when to my joy the solution occurred to me; and this was long after I had come to Down. The solution, as I believe, is that the modified offspring of all dominant and increasing forms tend to become adapted to many and highly diversified places in the economy of nature.

    We suggest that DAR 205.5: 148 is a plausible candidate for a note written in pencil as Darwin's carriage bumped along one of the lanes around Down House. But if this is correct there are two important qualifications, which make this more than a curiosity. First, this note would then not only be a record of the event remembered in the Autobiography, but it would also be the first in the series of notes dated November 1854. Second, the content of the note is in fact not the full blown Principle of Divergence, instead it is a statement of the problem of divergence. To paraphrase the note, 'only descent explains why classification produces a branching pattern'. This sets the problem; but how does that branching occur? Perhaps the solution had already occurred to Darwin during the course of the carriage ride. But he actually first enunciated the core idea in note DAR 205.9: 250 [1854.11.01], written on the same grey wove paper: 'There is no law of Progression, but times wd. give better chance of sports, & allow more selection; & all the organisms thus living an advantage, — a «free» competition of labour,— the result wd be more complicated & more perfect' (emphasis added). If this is the correct sequence, then DAR 205.5: 148 must also have been written on 1 November 1854, thus dating the problem and the solution to the same day. Sixteen years and one month after the Malthus episode, drawing once again on political economy, Darwin thought he saw how selection could produce the diversity of life.
Reproduced with the permission of the Syndics of Cambridge University Library and William Huxley Darwin
Higher resolution images available from Cambridge Digital Library
Transcription and apparatus © American Museum of Natural History