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Show 31.8 ' FERTILITY OF CROSSED CHAP. IX .. · The fe1~tility of the crossed plants is represented in the table by 100, and that of the s If-fertilised by the other figures. There are five .cases in '~hich the fertility of the self-fertilised plants IS approximately equal to that of the crossed ; nevertheless, in four of these cases the crossed plants were plainly t aller, and in the fifth somewhat taller than the self-fertilised. But I should state that in some of these five cases the fertility of the two lots was not strictly ascertaine l, as the capsules were not actually counted, from appearing equal in number and from all apparently containing a full complement of seeds. In only two instances in the table, viz., with V andellia and in the third generation of Dianthus, the capsules on the self-fertilised plants contained more seed than those on the crossed plants. With Dianthus the ratio b tween the number of seeds contained in the self-fertilised and crossed capsules was as 125 to 100; both sets of plants were left to fertilise themselves under a net; and it is almost certain that the greater fertility of the self-fertilised plants was here due mer ly to their having varied and become less stricti y dichogamous, so as to mature their anthers and stigmas 1norc nearly at the same time than is proper to the species. ExclnJing t~e seven cases now referred to, there remain twenty-siX in which the crossed plants were manifestly much more fertile, sometimes to an extraordinary degree, than the self-fertilised with which they grew in co~peti tion. The most striking i nstancos are those Ill which plants derived froln a cross with a fresh stock are compared with plants of one of the later self-fer· tilised generations ; yet there are so1ne striking cases, as that of Viola, between th intercrossed ph1nts of the same stock and the self-fertilis d, even in the first generation. The results 1nost to be trusted are those CHAP. IX. AND SELF-FERTILISED PLANTS. 319 in which the productiveness of the plants was ascertained by the number of capsules produced by an equal number of plants, together with the actual or average number of seeds in each capsule. Of such cases there are t"wel ve in the table, and the mean of their n1ean fertility is as 100 for the crossed plants, to · 59 for the self-fertilised plants. The Primulacem seem eminently liable to suffer in fertility fron1 selffertilisation. The following short table, E, includes four cases which have already been partly given in the last tf:tble. TABJ,E E.-Innate Fertility of Pla1ds from a Gruss with a fr esh Stock, compared wdh that of I nte1·crossed Plants of the same Stock, and with that qf Self-fertilised Plants, all of the correspond?: ng Generation. Fertility fudg ed of by the number or weight of seeds p roduced by an equal number of Plants. ----------------1------· MI~ULUS LUTEUs-the inter crossed plants are de-) l'lVed from a cross between two plants of the ! 8th self-fertilised gener ation. The self-fertilisedj plants belong to the 9th gener ation . . . . ESCHSCHO~T.ZIA CALIFORNICA~th e inter cr ossed and} self-fert1hsed plants belong to the_ '2nd generation DIANTHUS CARYOPHYLLUS-the intcrcross~d plants} are derived from self-fertilised of the Srd ge~ eration, crossed by intercrossed plants of the 3rd generation. The self-fertilised plants belong to the 4th generation. . . . . • . .) PE~~NIA VIOLACEA-the intercrossed and self-fer-} tlhsed plants belong to the 5th generation • . 100 100 100 100 4 3 45 40 45 33 54 46 ~.B.-In the above cases, excepting in that of Eschscholtzia, the plants denved from a cross with a fr esh stock belong on the mother-side to the same stock with the intercr ossed and self-fertilised plants, and to the corresponding generation. |