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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.
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.
The real nature of this state of the hereditary qualities is as yet wholly unknown. It would not be safe to formulate further conclusions before the evidence offered by the evening-primroses is considered. Thirdly, the question arises, whether the mutation is complete, not only as to the morphologic character, but also as to the hereditary constitution of the mutated individuals.
Even in the native field of the evening-primroses, no botanist would have discovered the rosettes with smaller or paler leaves, constituting the first signs of the new species. Only by the guidance of a distinct theoretical idea were they discovered, and having once been pointed out a closer inspection soon disclosed their number. Variability seems to us to be very general, but very limited.
If this were true, all chance of ever seeing a new species arise would be hopelessly small. Fortunately the evening-primroses exhibit contrary tendencies. One of the great points of pedigree-culture is the fact that the ancestors of every mutant have been controlled and recorded. Those of the last year have seven generations of known lamarckiana parents preceding them.
This species proved to be in a state of mutation, producing new elementary forms continually, and it soon became the chief member of my experimental garden. It was one of the evening primroses. Several evening-primroses have at different times been introduced into European gardens from America.
The production of new species of evening-primroses was observed on the field and afterwards duplicated in the garden. There is no reason to think that these cases are isolated instances. Quite on the contrary they seem to be the prototypes of repeated occurrences in nature.
Minor points of course will differ, but the main lines cannot have complied with wholly different laws. All so-called swarms of elementary species obviously pertain to a single type, and this type includes our evening-primroses as the only controlled case. Formulating the laws of mutability for the evening-primroses we therefore assume that they hold good for numerous other corresponding cases.
Quite on the contrary, it is at once evident that very simple rules govern the whole phenomenon. I shall now attempt to deduce these laws from my experiment. Obviously they apply not only to our evening-primroses, but may be expected to be of general validity.
Hence the conclusion that in comparing the two we must leave out the pedigree of the evening-primroses and consider only the group of forms as they finally show themselves. If in doing so we find sufficient similarity, we are justified in the conclusion that the drabas and others have probably originated in the same way as the evening-primroses.
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