My third point is of quite another nature and has not as yet been dealt
with. But as it appeals to me as the very soul of the problem, it seems
necessary to describe it in some detail. It does not refer to the new
type itself, nor to any of its morphologic or hereditary attributes, but
directly concerns the presumed ancestors themselves.
The peloric toad-flax in my experiment was seen to arise thrice from the
same strain. Three different individuals of my original race showed a
tendency to produce peloric mutations, and they did so in a number of
their seeds, exactly as the mutations of the evening-primroses were
repeated nearly every year. Hence the inference, that whenever we find a
novelty which is really of very recent date, the parent-strain which has
produced it might still be in existence on the same spot. In the case of
shrubs or perennials the very parents might yet be found. [582] But it
seems probable, and is especially proved in the case of the
evening-primroses, that all or the majority of the representatives of
the whole strain have the same tendency to mutate. If this were a
general rule, it would suffice to take some pure seeds from specimens of
the presumed parents and to sow and multiply the individuals to such an
extent that the mutation might have a chance to be repeated.
Unfortunately, this has not as yet been done, but in my opinion it
should be the first effort of any one who has the good luck to discover
a new wild mutation. Specimens of the parents should be transplanted
into a garden and fertilized under isolated conditions. Seeds saved from
the wild plant would have little worth, as they might have been partly
fertilized by the new type itself.
After this somewhat lengthy discussion of the value of observations
surrounding the discovery of new wild mutations, we now come to the
description of some of the more interesting cases. As a first example, I
will take the globular fruited shepherd's purse, described by Solms
Laubach as _Capsella heegeri_. Professor Heeger discovered one plant
with deviating fruits, in a group of common shepherd's purses in the
market-place near Landau in Germany, in the fall of 1897. They were
nearly spherical, [583] instead of flat and purse-shaped. Their valves
were thick and fleshy, while those of the ordinary form are
membranaceous and dry. The capsules hardly opened and therefore differed
in this point from the shepherd's purse, which readily loosens both its
valves as soon as it is ripe.
Public-domain text, read in full here on John Shaqi.
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