It should, however, be observed
that in some of the above cases, in which the crossed seeds were the
heaviest, as with Sarothamnus and Cyclamen, the crossed capsules
contained a larger number of seeds. Whatever may be the explanation of
the self-fertilised seeds being often the heaviest, it is remarkable in
the case of Brassica, Tropaeolum, Nemophila, and of the first generation
of Ipomoea, that the seedlings raised from them were inferior in height
and in other respects to the seedlings raised from the crossed seeds.
This fact shows how superior in constitutional vigour the crossed
seedlings must have been, for it cannot be doubted that heavy and fine
seeds tend to yield the finest plants. Mr. Galton has shown that this
holds good with Lathyrus odoratus; as has Mr. A.J. Wilson with the
Swedish turnip, Brassica campestris ruta baga. Mr. Wilson separated the
largest and smallest seeds of this latter plant, the ratio between the
weights of the two lots being as 100 to 59, and he found that the
seedlings "from the larger seeds took the lead and maintained their
superiority to the last, both in height and thickness of stem." (9/17.
'Gardeners' Chronicle' 1867 page 107. Loiseleur-Deslongchamp 'Les
Cereales' 1842 pages 208-219, was led by his observations to the
extraordinary conclusion that the smaller grains of cereals produce as
fine plants as the large. This conclusion is, however, contradicted by
Major Hallet's great success in improving wheat by the selection of the
finest grains.
Pages:
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504