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Show OuAP. II. 54 IP01\HEA PURPUREA. It should be especially observed that the_a:verage difference between the crossed and self-fert1hsed plants is not due to a few of the former having grown to an extraordinary height, or to a few of the self-fertilised being extremely short, but to all the crossed rlants havin"" surpassed their· self-fertilised opponents, with the f:w following exceptions. The first occurred in the sixth generation, in which the plant named" Hero" appeared; two in the eighth ?enerati~n, but the selffertilised plants in this generatwn were man anomalous condition, as they grew at first at an unusual rate and conquered for a time the opposed crossed plants ; and two exceptions in the ninth generation, though one of these plants only equalled its crossed opponent. Therefore, of the seventy-three crossed plants, sixtyeight grew to a greater height than the self-fertilise(l plants, to which they were opposed. In the right-hand column of figures, the difference in height between the crossed and self-fertilised plants · in the successive generations is seen to fluctuate much, as might indeed have been expected from the small number of plants measured in each generation being insufficient to give a fair average. It should be remembered that the absolute height of the plants goes for nothing, as each pair was measured as soon as one of them had twined up to the summit of its rod. The great difference in the tenth genera· tion, viz., 100 to 54, no doubt was partly accidental, though, when these plants were weighed, the differimce was even greater, viz., 100 to 44. The smallest amount of difference occurred in the fourth and the eighth generations, and this was apparently due to both the crossed and self-fertilised plants having become unhealthy, which prevented the former attain· ing their usual degree of superiority. This was an CHAP. II. SUMMARY OF OBSERVATIONS. 55 unfortunate circumstance b t . . not thus vitiated as b th' l u my expenments were t h ' ~ o ots of plant . . o t e same condition h h s were exposed favourable. s, w et er favourable or un- There is reason to believe h Ipomooa, when growino· out tf ~t the flowers of this , d b . o 0 CtOOrS are h b't cr?sse y msccts, so that the fir ' . : a 1 ually raised from purchased l st seedlmgs whi.ch I of a cross. I in;'er tl:~etctsh':er~ probably the offspring urn e-bees often visitino- the e, rst y from h bl lS Is the cas :f:i • 1 quantity of pollen left b oth flowers, ancl from the fl Y om on the st · . f owers ; and sccondl f. Igmas o such same lot of s~ed var·y!ln' arom tthle ~lants raised from the (, b grea y 1n th 1 flowers, for as we sh ll h . . e co our of their h . a ereafter see th' . a· muc 1ntercrossing * It · ' Is In 1cates th · Is therefo · at the plants raised b f re, remarkable in all probability self/.~~ ~om flowers which were many generation's of- er 1 :sec for the first time afte~ markedl . f·' •· . c_rossing, should have been y m enor m hewht to th . so as they \vere namely o 76 e Intercrossed plants wh .w h w. ere sel'f -fe~ rtilise'd aisn ht o 100 . .A s the plants necessarily became much =~r succeedm? generation . the later than in the ·r . e cl~sely mterbred in been expected that tehar ll~~"generat~ons, it might have u e c 1uerence h · them aD.d the crossed pla t In eight between · · n s would have creasmg; but, so far is this f· . gone on in-the difference between th ;om bemg the case, that seventh, ei.,.hth and . the wo s~ts of plants in the is less than in the fi .... tnlnd generations taken together W hen however I:5 an . second gen erat 'I ons too·ether ' , we remember th t h 5 · and crossed plant . ll a t e self-fertilised s are a descended from th e same tio*n Vdeersl ot sn·y s, (..'. s, m· 1a Produc-t! t Y arJetes, 1865 p. 6'!) alllaie dc orl tam van·e t ·l e::'l of a' close]u y p ant, the Convolvulus tri-gcorloowr, nc aant naodt ' b·te ke Pt pure unless varietie ls ance from all other s. |