distinction. Darwin's variations, which from time to time happen to arise,
are MUTATIONS, the opposite type being commonly designed fluctuations. A
large mass of facts, collected during the last few decades, has confirmed
this view, which in Darwin's time could only be expressed with much
reserve, and everyone knows that Darwin was always very careful in
statements of this kind.

From the same chapter I may here cite the following paragraph: "Thus as I
am inclined to believe, morphological differences,...such as the
arrangement of the leaves, the divisions of the flower or of the ovarium,
the position of the ovules, etc.--first appeared in many cases as
fluctuating variations, which sooner or later became constant through the
nature of the organism and of the surrounding conditions...but NOT THROUGH
NATURAL SELECTION (The italics are mine (H. de V.).); for as these
morphological characters do not affect the welfare of the species, any
slight deviation in them could not have been governed or accumulated
through this latter agency." ("Origin of Species" (6th edition), page
176.) We thus see that in Darwin's opinion, all small variations had not
the same importance. In favourable circumstances some could become
constant, but others could not.

Since the appearance of the first edition of "The Origin of Species"
fluctuating variability has been thoroughly studied by Quetelet. He
discovered the law, which governs all phenomena of organic life falling
under this head. It is a very simple law, and states that individual
variations follow the laws of probability. He proved it, in the first
place, for the size of the human body, using the measurements published for
Belgian recruits; he then extended it to various other measurements of
parts of the body, and finally concluded that it must be of universal
validity for all organic beings. It must hold true for all characters in