The mutation theory; experiments and observations on the origin of species in the vegetable kingdom . these flowered, but only 18 of them produced suf-ficient seed. Two of them had hereditary values of 14and 16%, the rest from 0 to 7%, with a mean of 4%.In 1896 only the tricotyls of the parent with 16% wereplanted out. There were 39 of these, and for all of thema value could be calculated. These values have been oivenon page 422, and were above 50% for eight plants. Theintermediate race, therefore, was already represented byseveral specimens. In 1897 I planted out only the tricotylous seedling
The mutation theory; experiments and observations on the origin of species in the vegetable kingdom . these flowered, but only 18 of them produced suf-ficient seed. Two of them had hereditary values of 14and 16%, the rest from 0 to 7%, with a mean of 4%.In 1896 only the tricotyls of the parent with 16% wereplanted out. There were 39 of these, and for all of thema value could be calculated. These values have been oivenon page 422, and were above 50% for eight plants. Theintermediate race, therefore, was already represented byseveral specimens. In 1897 I planted out only the tricotylous seedlingsof the ])lant with 64%, and saved the seeds of 39of them. Their hereditary values were distributed be- 430 Tricotylous Races. tween 16 and 79% and gave a mean of 49%. The racecould therefore be regarded now as perfectly pure. Hclichrysiuii hractcatuni conipositum, Fig. 86. Fromthe same set of sowings as that which contained Clarkia,I planted out some tricotylous seedlings of was a relatively large number of them, and alto-gether 19 set seed. For each one the value was calcu-. Fig. 85. Clarkia piilchcUa alba. A flowering sprig. lated se])arately. In the case of 15 plants these weredistributed between 2 and 8% and exhibited a mean of4% ; but there were higher figures besides, viz., 12—12—16 and 41%. The latter plant was obviously a repre-sentative of the intermediate race sought for; the re-mainder were thrown away as doubtful, although ifthere had not happened to be such a faA^orable plant The Isolation of Tricofyloiis hitcniicdiatc Races. 431 among them all, the plant with 16% would, no doubt,have offered me as good a prospect as the correspondingplant of Clarkia. The chosen plant was remarkable forthe large proportion of tetracotyls and the low proportionof hemi-tricotyls which it produced. There were 11 %of the former, and only 1 % of thelatter. This peculiarity has reappearedamongst its descendants, especially withregard to the tetracotyls. In 1895 I
Size: 1471px × 1699px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookpublisherchicagoopencourtpu
