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Show CHAP. II. IPOM<EA PURPUREA. 50 ]f , that a cross between the se - 1I.S O d pl'"'nts It is therefore clear d ce any beneficial effect w • d · d not pro u . 1 fertilised children ?f_Hero ;oubtful whether this ne?ative res:u ~ worth notice; and lt IS very f ct of brothers and sisters havmo can be attributed merely ~o the. atercrossed plants of the several been united for the ordinary In h e been derived from the ' · st often av 11 successive generatwns ~u as shown in Chap. I.), and yet a union of brothers and siste~s r( to the self-fertilised plants. We of them were greatly supeno . . which we shall soon sec . t the suspiCIOn, 1' are therefore dnven o 'tt d to its offspring a pecu mr d tl t Hero transmi e strengthene ' la r self-fertilisfLtion. constitution adapted fo lf f tilised descendants of Hero It would appear that the se - er er of oTmvth equal to 't d f·om Hero a pow o have not only inhen e r d 1 t but have become more that of the· ordinary ~~tercross: i~ ~~u~l with the plants ~f the fertile when self-fertilised tha th If-fertilised grandchildren present speC·ie s. The flowers o.n hthe sgee neration of self·- f·e r t·l · d I Ise of Hero in Table XVI. ~thehe~g polle~ and produced plenty t .l. d with t eu own i! plants) were fer I Ise . ·hou h this is too few a number lOr a of cap$ules, ten of whiCh (t g . sule -a hio·her average . d 5 . 2 seeds per cap ' o safe average) containe . 'th the self-fertilised plants. l · other case WI . . than was observec In any ese self-fertilised grandchildren were The anthers produced by th . d s much I)Ollcn as those on d 1 d and containe a . 1 also as well eve ope c:~I·ng generatiOn; w lei.e as 1 t f the corrcspon -L f the intercrossed P an ,s ~ dinar~ self-fertilised plants o this was not the case with the or J e few of the flowers · N ertheless som the later generatwns. ev f' H were slio·htly monstrous, d h'ldren o ero o produced by the gran c 1 t.1. d lants of the la,tcr genera-like tho.·c of the ordinary self-fer I Ise b? t of fertility I may add t.ions. In order not to re_c~r to the ;u ~e~pontancously produced that twenty-one self-fertilised capsu es, . . the ninth o·encration by the great-grand ch I'l dr e.n of Hero (forming 4. 47 · soe eds . an d . . t ) t ·ned on a.n average ' of self-fertilised plan s 'con m lf-f tilised flowers of any this is as high an average as the se er generation usually yielded. . . d randchildron of Hero in Several flowers on the self-fertlhse .g " h :flower. and Table XVI. were fertl.l 1.s e d Wl' th P0 llen from t e same ' . • _, 1 'ldren of Hero) tho seedlings rm.s e d fr om the m (grea.t -oo ranSu c n ":.tl other flowers formed the ninth self-fertilised genera bon. cdv?hi\d so that they were crossed WI' th po 11 en fr·o m another ghr an c dI si'' sters and t hc may be considered as t h e o~us pri·n oo· of bro.t ers an d gi·ca't -arand· 11 d the vntercrosse " o seedlings thus raised may be ca e f t'lised with pollen children. And lastly' other flowers were er 1 CHAP. II. SUMMARY OF OBSERVATIONS. 51 from a distinct stock, and the seedlings thus raised may be called the Colchester-crossed great-grandchildren. In my anxiety to see what the result would be, I unfortunately planted the three lots of seeds (after they had germinated on sand) in the hothouse in the middle of winter, and in consequence of this the seedlings (twenty in number of each kind) became very unhealthy, some growing only a few inches in height, and very few to their proper height. The result, therefore, cannot be fully trusted· and it would be useless to give the measurements in detail. fu order to str·ike as fair an average as possible, I first excluded all the plants under 50 inches in height, thus rejecting all the most unhealthy plants. The six self-fertilised thus left were on an average 66 · 86 inches high; the eight intercrossed plants 63 · 2 high; and the seven Colchester-crossed 65 · 37 high; so that there was not much difference between the three sets, the selffertilised plants having a slight advantage. Nor was there any groat difference when only the plants under 36 inches in hejght were excluded. Nor again when all the plants, however much dwarfed and unhealthy, were included. In this latter case the Colchester-crossed gave the lowest average of all; and if these plants had been in any marked manner superior to the other two lots, as from my former experience I fully expected they would have been, I cannot but think that some vestio·e of such . . b superwnty would have been evident, notwithstanding the very unhealthy condition of most of the plants. No advantage, as far as we can judge, was derived from intercrossing two of the grandchildren of Hero, any more than when two of the children were crossed. It appears therefore that Hero and its descendants have varied from the common type, not only in acquiring great ~o~e~ of: growth, and increased fertility when subjected to selffertrhsatwn, but in not profiting from a cross with a distinct stock; and this latter fact, if trustworthy, is a unique case, as far as I have observed in all my experiments. Summary on the Growth, Vigowr, and Fertility of the successive Generations of the crossed and selj'-jert(llised Plants of Ipomma purpu·rea, together with smne niiscellaneous Observations. In the following table, No. XVII., we see the average or rn.ean heights of the ten successive generations ol the Intercrossed and self-fertilised plants, grown in E 2 |