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Vries, Hugo de, 1848-1935

"Species and Varieties, Their Origin by Mutation"

Many trials may be necessary
to secure the special race. I had the good fortune to find two plants of
clover, bearing one quinate and several quaternate leaves, on an
excursion in the neighborhood of Loosdrecht in Holland. After
transplanting them into my garden, I cultivated them during three years
and observed a slowly increasing number of anomalous leaves. This number
in one summer amounted to 46 quaternate and 16 quinate leaves, and it
was evident that I had secured an instance of the rare "five-leaved"
race which I am about to describe.
Before doing so it seems desirable to look somewhat closer into the
morphological features of the problem. Pinnate and palmate leaves often
vary in the number of their parts. This variability is generally of the
nature of a common fluctuation, the deviations grouping themselves
around an average type in the ordinary way. Ash leaves bear five pairs,
and [342] the mountain-ash (_Sorbus Aucuparia_) has six pairs of
leaflets in addition to the terminal one. But this number varies
slightly, the weaker leaves having less, the stronger more pairs than
the average. Such however, is not the case, with ternate leaves, which
seem to be quite constant. Four leaflets occur so very rarely that one
seems justified in regarding them rather as an anomaly than, as a
fluctuation.


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