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Show IPOl\HEA PURPUREA. CHAP. II. 34 t llest self-fert.il i.s ed p !ants were only 15 and whilst the t:o he~ght, or as 100 to 59. lots of the same seeds 12.5 .Inch~s wed at the same time twoh d and covcrccl with I likewise so h · h was s a Y " t in a part of the gardend l'w gsIC from the fir t looked. the mos 1 • 1 . d The crossed see In . l to a hejo·ht of 7-r Inc les' wee s. · d up a stick on Y b ll d the l t9a lthy ' but thef y tt'wliisneed were no t a blc t.o twine at a ; an whilst the self- er I nly 3!- inches in hClght. . the midst of t ll st of them was o 2 ds were sown In a Lea stly t wo lots of the . same se·c g Vl. crorous ly · The seedlings 'cand -tuft (Ibens) g~owin b on diccl excepting one, a bed of b t ~ll the self-fertilised oneshs? ht of only 4 inches. came uP' u d grew to a m g · 1 · which never twined an . . on the other hand, su~vivcc '. M y of the crossed seedlmgs, f the Iberis to the hmgh_t of ::some twined up the ste~s o that the crossed seedlmgH ~1 inches. These cases prove the self-fertilised, both when have an ilnmense advantage ov;r vourable conditions, and when growing isola ted .u_nder :erye:~ a other or with other plant.·, as t into competitiOn with . wpuo uld happen I· n ast at.e of nature,..; the Four· th Ge.nera t w· n.-Seed- Orossed and se?f-fertil~sed Plftnts o~ sed and self-fertili ed plants lings raised as b ef re from the eros f llows ·- 0 . . T bl III. gave results as 0 ' · th' d generatiOn In a e ' of the lT T V (Fourth Ueneratiurt.) ABLE - No. of Pot. I Crossed Plants. Self-fertilised Plimts. ,- -I Inches. lnch(•S. 1- I. 84 80 44~ I 47 - - - 731 I Il. 83 59 51i HI. 82 5G~ 6G! G~3 68 52 --- 421•0 -. Total inches. I 488•5 I . f th seven crossed plan ts is 69·78, Here the average hmght o ~~-fertilised pla.nts GO ·14 ; . or ~s inches, and that of the seve~ se - relatively to· that m t e 100 to 86. This smaller drffe:renced t the plants having been former generatiO· ns, may be at.t nbutc d oo nsequcntly toth ou··n ot raised during the depth of winter, an c CHAP •. II. CROSSED AND SELF-FERTILISED PLANTS. 35 having grown vigorously, as was shown by their genel'al appearance and fTom several of them never reaching the summits of the rods. In Pot II., one of the self-fertilised plants was for a long time taller by two inches than its opponent, but was ultimately beaten by it, so that all the crossed plants exceeded their opponents in height. Of twenty-eight capsules produced by the crossed plants fertilised by pollen from a distinct plant, each contained on an average 4·75sceds; of twenty-seven selffertilised capsules on the self-fertilised plants, each contained on an average 4 · 4 7 seeds ; so that the proportion of seeds in the crossed and self-fertilised capsules was· as 100 to 94. Some of the same seeds, from which the plants in the last Table V. had been raised, were planted, after they had germinated on damp sand, in a square tub, in which a large BTugm~ nsia had long been growing. The soil was extremely poor and full of roots; six crossed seeds were planted in one corneT, and six self-fertilised seeds in the opposite corner. All the seedlings from the latter soon died excepting one, and this grew to tho hejght of only 1~ inches. Of the crossed plants three survived, and they grew to the height of 2~ inches, but were.not able to twine round a stick; nevertheless, to my surprise, they produced some small miserable flowers. The crossed plants thus had a decided advantage over the self-fertilised plants under this extremity of bad conditions. Crossed and self-fertilised Plunts of tlze Fifth Generation.-These were raised in the same manner as before, and when measured gave the following results:- TABLE VI. (Fifth Gene1·ation.) No. of Pot. Crossed Plants. Self-fertilised Plants. I. Inches. Inr:hes. 96 73 86 78 69 29 II. - 84 51 84 8·t 76! 59 Total inches. 495·13 374•00 The aver·age height of the six crossed plants is 82 ·54 inches, D 2 |