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Some undescribed forms were quite sterile, and some I observed which produced no flowers at all. From this statement it may be seen that nearly all qualities vary in opposite directions and that our group of mutants affords wide material for the sifting process of natural selection.
The lata mutants having an odd chromosome are almost completely male-sterile, and their seed production is also much reduced: but this partial sterility cannot be attributed entirely to the odd chromosome because semilata, which has also 15 chromosomes, does not show the same degree of sterility.
The fact seems to be, according to other parts of Gates's volume, that there are various races of Lamarckiana in English gardens and in the Isle of Wight, as well as in Sweden, etc., and that these races differ from one another less than the mutants of De Vries and his followers. An important point about these mutations is that their production is a constant feature of Lamarckiana.
From this they have inherited the mutability or the capacity of producing at their turn new mutants. But they seem to have done so incompletely, changing in the direction of more absolute constancy. This was especially observed in the case of rubrinervis, which is not of such rare occurrence as O. gigas, and which it has been possible to study in large numbers of individuals.
The mutation theory of De Vries is a much more convincing theory of the origin of species than is Darwin's Natural Selection. If things would only mutate a little oftener! But they seem very reluctant to do so. There does seem to have been some mutation among plants, De Vries has discovered several such, but in animal life where are the mutants?
It can neither be constrained by selection if it is absent from the beginning, nor does it need any natural or artificial aid if it is present. Most of my new species have proved constant from the first. Whenever possible, the original mutants have been isolated during the flowering period and artificially self-fertilized.
If the absence of pigment from the lower side in normal Flat-fishes is due to the absence of light, how is it that the pigmentation persists on the lower side of ambicolorate specimens, which is no more exposed to light than in normal specimens? The answer is that in the mutants the determinants for pigmentation are united with the determinants for the lower side of the fish.
As is easily understood, these were related as "nieces" to the first observed mutants. They originated in quite the same way, by a sudden leap, without any preparation and without any intermediate steps. Mutation is proved by this experience to be of an iterative nature. It is the expression of some concealed condition, or as it is generally called, of some hidden tendency.
Last but not least important it affords material for a complete systematic and morphologic study of the newly arisen group of forms. The physiologic laws, however, which govern this process are only very imperfectly revealed by such a study. The instances are too few. Moreover the seeds from which the mutants spring, escape observation.
In doing so we find the same main feature, the minute differences in nearly all points. V. The same new species are produced in a large number of individuals. This is a very curious fact. It embraces two minor points, viz: the multitude of similar mutants in the same year, and the repetition thereof in succeeding generations. Obviously there must be some common cause.
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