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Show CHAP. IX. 352 WEIGHT AND GERMINATION OF 1 • adduced, incniding the Considering the facts .nto.w hi. ch are more fertile h vane Ies w appearance of t o~e t nd than the intercrossed and taller than then pard~n s :eneration, it is difficult f th correspon Ing b . . · plants. o e .. on that self-fertilisation Is In some to avoid the suspiCI h ·h I. f this be really the t ous. t oug . . . respects ad van age ' . a rule quite 1nsign1fi-h advantage IS as . d' . t cas ' any sue . h that from a cross with a Ishnc cant compared wit "th le of a fresh stock. Should I)lant, and esciapllye WI f·t OI, verified it would t h row · · be herea er ' . this suspicion . the next chapter, on the exJst-light, as we shall s~e m ll and inconspicuous flowers ence of plants beal~l~f ~ln: insects, ' and therefore are w hi eh are rare] y VlSI e y rarely in tercrossed. d p . d of Gern~ination of Seeds Relative Weight an . _.f. er2~. d Flowers - ..A .. n equal from crossed and self-J ert2 "'fse t. r sed with pollen from f d from flowers er 1 I . number o· see s fl , f ·tilised with theu O\Vl1 h l t and from owers er r~l . (:"tnot er P an ' 1 · ixteen cases. 1eu I)ollen, wer, e '\\r e1• ghed ' b. ut on. Y tIhn s followino· h.s t ; t h at · ht ·e o·Iven 1n e b relative weig s ar b d fio,vers beincr taken as 10 0. of the seeds from the crosse b IrJomcea purpurea (pareut plant.? ) . (third generatiOn . Sal d" a cocci"n ea Brassica oleracea . · · • : ). lb~ris umbellata (second generatiOn Delphinium .con.oliua . Hibiscus afncanus Tropreolum minus · · Lathyrus odoratus (~bout) Sarothamnus scopanus . Specularia ~pe~ul~m · · Nemophila ms1gms · · Borago offieinalis • · · Cyclamen persicum (nbout) Fa 0 )yrum eseulentmn · · · . · • .., g 1 Canna wa1.s cewiczi (three "2 :enerat10n::-,) · It is reinarkable that in ten out of as 100 to 127 87 " " 100 " " 103 " " 136 " " 45 " " 105 " " ]1.') " " ]'()() " " 88 " " 86 " " 105 " " 111 " " 50 " " 82 " " 102 " " these sixteen CHAP. IX. CROSSED f\ND SELF-FERTILISED SEEDS. 353 cases the self-fertilised seeds were either superior or equal to the crossed in weight; nevertheless, in six out of the ten cases (viz., with Ipon1cea, Salvia, Brassica, Tropmolum, Lathyrus, and Nemophila) the plants raised from these self-fertilised seeds were very inferior in height and in other respects to those raised from the crossed seeds. The superiority in weight of the selffertilised seeds in at least six out of the ten cases, namely, with Brassica, Hibiscus, Troproolum,N e1nophila, Borago, and Canna, may be accounted for in part by the self- fertilised capsules containing fewer seeds; for when a capsule contains only a few seeds, these will be apt to be bette.r nourished, so as to be heavier, than when many are contained in ·the same capsule. It should, however, be observed that in some of the above cases, in which the crossed seeds were the heaviest, as with Sarotha1nnus and Cyclamen, the crossed capsules contained a largo~ number of seeds. Whatever may Le the explanation of the self-fertilised seeds being often the heaviest, it is remarkable in the case of Brassica, Tropoool um, N emophila, a~d of the :fhst generation of Ipomcea, that the seedlings raised fron1 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 Lathyru.~? odoratus; as has Mr. A. J. vVilson with the swedish turnip, Brassica campestris ruta baga. . Mr. Wilso11 separated the largest and s1nallest seeds of this latter plant, the ratio between the \\ ei o·hts 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 thick- 2 A |