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Show CHAP. I. INTRODUCTORY REMARKS. 16 fi . t to last to the same age, were su bJ' e cted frorn d rds f·om the same pare.n t s. . . d were descen e r . . condrtwns, an . pairs of plants '' Ie When only from two to srx 'festly of little or no h ul ts are roanr measured, t e res th y confinn and are con-value, excep t r· n .s o far as d e a larger scale wr· t h b enments ma e on firmed Y exp . . the report on the seven other species. I wrll now ;.rv:_ Mr Galton has had the tables of measurements, w rc . reat kindness to draw up for me. . g nts of the plants Wlth care, "I have examined the measure~e fi d out how far the means and by many statistical metho~~~s~an ~ ren.li ties, such as would of the several sets represent 1 conditions of arowth come out the same so long as_ th_e glene;:hods that w rc adopted remained unaltered. The prn~c~p~ m of the shorter series are eas1' ly explained by selectlng one1 " of plants, say of Zea mays, for an examp c. Zea mays (young plants). I I ARRANGED IN 0JWER OF 1\IAG:!"ITUD~ As recorded by Mr. Darwin. \ In ~ Single cries. I In Separate Pots. '----:----~-~ I I 1- VI. 1 VII. I VIII. Column L II. HI. IV. V. --- ----- ~- ~L. Difference ',------~-Cr--os-s.ed. Sclf-fert. Cros ·ed. I Self-fert. ~~ --- -- ------ ------ Inches. lncll ·. I Inches. Pot 1. Pot II. Pot III. Pot IV. Inches. Inches. Inches. 2o :1 - :3 ~ lnchcs. 23 4 20 .ll·J 23!!" il o 23 ~ 17 ~ ll 20 - 3 ~ 12 20~ 21 20 23~ 20 - :3 21 2() 12 17~ ;~k 185 - 3~ 22 20 22~ 18 ~ - 3~ 22 ~ 20~ 18~ 2q 23~ 21 22~ 23 12 i~3ll 21~ 18a 22 18 ~ - 3~ 18-g:' .l 215 18 - 3 ~ 18~ 19~ B 18 _ ;) 4 21 1 18~ 15~ 16 ~ 18 16~ 23§ 22 ~ 21 § 20# 18i 23 22~ 21 12 18~ 18 16a 16 ~ 1t-:>2g 18 18 15~ 12~ 21 1 - 3 21 11 ~ 1 - :)~ 20t3 11! 4 -:1~ v 19~ lG ~ \ - 2 ~ 18 ~ 15 * - 2 ~ 12 0 1 5~0 + :3 * 0 12 12~ +U(is CHAP. I. INTRODUCTORY REMARKS. 17 "The observations as I received them are shown in columns II. and III., where they certainly have no prima jucie appearance of regularity. But as soon as we arrange them in the order of their magnitudes, as in columns IV. and V., the case is materially altered. We now see, with few exceptions, that the largest plant on the crossed side in each pot exceeds the largest plant on the self-fertilised side, that the second exceeds the second, the third the third, and so on. Out of the fifteen cases in the table, there are only two exceptions to this rule. We may therefore confidently affirm that a crossed series will alwayR be found to exceed a self-fertilised series, within the range of the conditions under which the present experiment has been Inade.'' Pot. Crossed. Self-fert. I Difference. I. 18~ 19 § I +O~ II. 20~ 19 -q III. 2Jb 16~ -4g IV. 19g 16 -3~ "Next as regards the numerical estimate of this excess. The mean values of the several groups are so discordant, as is shown in the table just given, that a fairly precise numerical estimate seems impossible. But the consideration arises, whether the difference between pot and pot may not be of much the same order of importance as that of the other conditions upon which the growth of the plants has been modified. If so, and only on that condition, it would follow that when all the measurements, either of the crossed or the self-fertilised plants, were combined into a single series, that series would be statistically regular. The experiment is tried in columns VII. and VIII., where the regularity is abundantly clear, and justifies us in considering its mean as perfectly reliable. I have protracte<l these measurements, and revised them in the usual way, by drawing a curve through them with a free hand, but the revision barely modifies the means derived from the original observations. In the present, and in nearly all the other cases, the difference between the original and revised means is under 2 per cent. of their value. It is a very remarkable coincidence c |
