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As was to be expected, lata and nanella were repeated in this third generation . I was sure to get nearly all of them, without any important exceptions, as I now knew how to detect them at almost any age. In fact, I found many of them; as many as 60 nanella and 73 lata, or nearly 5% of each. Rubrinervis also recurred, and was seen in 8 specimens.
If there had been any visible preparation towards the coming mutation, it could not have escaped observation. Moreover, if visible preparation were the rule, it could hardly go on at the same time and in the same individuals in five or six diverging directions, producing from one parent, gigas and nanella, lata and rubrinervis, oblonga and albida and even scintillans.
Moreover I observed that the attributes of lata and nanella, which I now studied in the offspring of my first mutants, were clearly discernible in extreme youth, while those of rubrinervis remained concealed some weeks longer. Hence I concluded that the young plants should be examined from time to time until they proved clearly to be only normal lamarckiana.
Varieties differ from their species clearly in one point, and this is either a distinct loss, or the assumption of a character, which may be met with in other species and genera. laevifolia is distinguished by the loss of the crinkling of the leaves, brevistylis by the partial loss of the epigynous qualities of the flowers, and nanella is a dwarf.
But the character by which the plants may be most easily recognized from a distance in the field is the failure of the fruits. They were found there nearly every year in varying, but always small numbers. Leaving the short-styled primrose, we come now to the last of our group of retrograde varieties. This is the O. nanella, or the dwarf, and is a most attractive little plant.
Concerning inheritance of these characteristics nothing can be directly asserted because of the lack of pollen. The new type can only be perpetuated by crosses, either with the parent form or some other mutant. I have fertilized it, as a rule, with lamarckiana pollen, but have often also used that from nanella and others. In doing so, the lata repeats its character in part of its offspring.
The faculty of producing nanella or lata remains the same through all the years. This faculty must be one and the same for all the hundreds of mutative productions of the same form. When and how did it originate? At the outset it must have been produced in a latent condition, and even yet it must be assumed to be continuously present in this state, and only to become active at distant intervals.
It fulfilled my hopes, and at once gave proof of the possibility of the direct observation of the origin of species, and of the experimental control thereof. The third generation was in the main a repetition of the second. I tried some 10,000 seedlings and found three lata and three nanella, or nearly the same proportion as in the first instance.
Oblonga was observed at times to constitute as much as 1% or more of the sowings of scintillans, while lata and nanella were commonly seen only in a few scattering individuals, although seldom lacking in experiments of a sufficient size. Secondly the instability seems to be a constant quality, although the words themselves are at first sight, contradictory.
The second generation was sown in 1888 and flowered in 1889. It at once yielded the expected result. 15,000 seedlings were tested and examined, and among them 10 showed diverging characters. They were properly protected, and proved to belong to two new types. 5 of them were lata and 5 nanella. They flowered next year and displayed all the characters as described in our preceding lecture.
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