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Show 340 SELF-STERILE PLANTS. CHAP. IX. ·t· 11 self-sterile, producing The other plant was par Ia y . f 11 1 any of which were o sma very few capsu es, ~ this lant had grown tall, size When however, p d . h the · uppermo' st b r.a nc hes became presse. . against bt e net and grew cr.o o k e d ' and in this position thh e ceds k th flowers throucrh the roes es, an were able to sue 8 b. . b · 1 t . 11 t them from the neigh onnng p an s. brought po en ° · · h 1 These branch es then beca1ne load.e d. wit capsu, . es. ; h . d lower branches remainlng almost uarc. the ot er an · · h f' rrho sexua1 cons t1.t llti. on of this species IS t ore oro sinlilar to that of Reseda odorata. Concluding Remarks on selj-stm~ile Plants. In order to favour as far as possible the self-fertilisation of some of the foregoing plants, all the flowers on Reseda odorata an~ some of those on th~ Abutilon were fertilised with pollen. from . other flowers on the same plant, instead of with then own ollen, and in the case of the Senecio with ~ollen from ~ther flowers on the same corymb; but _this mad~ no d.ff ·n the r sult Fritz Mii.llcr tned both lnnds I erence 1 · . . r b . . f self- fertilisation in the case of B~gnoni~, ra ern~ :o:ritana and Abutilon, likewise with no difference m the result. With Eschscholtzia, however, he found that pollen from other flowers on the same pla~t W'1S a little more effective than pollen from t e c' c:: fl T • • So did Hildebrand* in Germany; as same o" er. 1 · thus thi.rteen out of fourteen flowers of Eschscho tzia fertilised set capsules, these conta1· n·i ng on an average c (, t g. 5 seeds . whereas only fourteen flowers out of twenl y- one fertil'i sed with their own P0 11 en so t .c dap bsu esd, these containing on an average 9 . 0 see d s. Hil e ran * , Pringsh~im's Jahrbutb. fu.. r w1· ss. Bo t a nil~:'' vii. P· 467. CHAP. IX. SELF-STERILE PLANTS. ::541 found a trace of a similar difference with Corydalis cava, as did Fritz Muller with an Oncidiun1.* In considering the ·several cases above given of complete or almost co1nplete self-sterility, we arc first struck with their wide d.istributi_on throughout the vegetable kingdom. Their number is not at present large, for they can be discovered only by protecting plants from insects and then fertilising then1 with pollen fr01n another plant of the sa1ne species and with their own pollen ; and the latter must be proved to be in an efficient state by other trials. Unless all this be done, it is impossible to know whether their self-sterility may not be due to tho male or female reproductive organA, or to both, having been affectecl by changed conditions of life. As in the course of my experiments I have found three new cases, and as Fritz Muller has observed indications of several others, it is probable that they will hereafter be proved to Le far from rare.f As with plants of the same species and parentage, some individuals are self-sterile and others self-fertile, of which fact Reseda odorata offers the most striking instances, it is not at all surprising that species of the same genus differ in this san1e manner. Thus Verbascu1n phr:Enieeum and nigrum are self-sterile, whilst V. thapsus . and lyelinitis are quite self-f~rtile, as I know by trial. There is the same difference between some of the species of Papaver, Corydalis, and of other genera. Nevertheless, the tendency to self-sterility certain! y runs to a certain extent in groups, as we see * ' Variation under Domesti?~ tion,' chap. xvii. 2nd edit. vol. 11. )Jp. 113-115. t Mr. Wilder, the editor of a ~orticulturaljournal in the United Stutes (quoted in ' Gardeners' Chronicle,' 1868, p. 1286) states that Lilium cmratum, Impatiens pallicla and fu.lva, an.l Forsythia vi1'1:clissima, cannot be fcrtili ed with their own pollen. |