A manual of Mendelism / by James Wilson.

  • Wilson, James, 1861-1941.
Date:
1916
Catalogue details

Licence: In copyright

Credit: A manual of Mendelism / by James Wilson. Source: Wellcome Collection.

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    field to revert once again to the plough without the artificial and precarious stimulus of a protective duty. But how are these new varieties to be produced ? The way has been already shown by such workers as Patrick Shirreff and the staff at Svalof in Sweden. There were other raisers of new varieties before Shirreff, but none so long persistent and none whose work illustrates better what can and what cannot be done without Mendel’s law. Shirreff tells us how he began to raise new varieties on his farm in East Lothian : “ When walking over a field of wheat on the farm of Mungoswells, in the county of Haddington, in the spring of 1819, a green, spreading plant attracted my notice, the crop then looking miserable from the effects of a severe winter ; and next day measures were taken to invigorate its growth by removing the surrounding vegetation and supplying manure to the roots. In the course of the summer several stalks were cut down by hares ; but, notwithstanding this loss to the plant, sixty-three ears were gathered from it at harvest, yielding 2473 grains, which were dibbled in the following autumn at wide intervals. For the two succeeding seasons the accu- mulating produce was sown broadcast, and the fourth harvest of the original plant amounted to about 42 qr. of grain fit for seed ; and proving to be a^new variety, it was named Mungoswells wheat.” For thirty years Shirreff persisted in this work of selecting single plants in his own and his neighbours’ fields and testing and accumulating stocks till he had given the world a large number of new varieties. Then came the tragedy. He began crossing, and, as we should now expect, his crosses did not breed true but were so variable that he became bewildered in the