OCR Text |
Show CHAP. II. IPOMCEA pURPUREA. 56 f the crossed p1 a nt s in each mother-plant, that many o 1 ely related, and that . . 1 ted often c os . h generation were re a ' ditions whic ' as we d t the same con ' · all were expose d 0 · very 1. mpo rtant circumstance, 1t shall hereafter fin ' ~s. a hat the difference between lS not at all surpnsing th t decreased in the later them should have somew a t y an astonishing fact: . It . on the con rar ' . . generations. IS, should have been v1ctonous, that the crossed plants the self-fertilised plants even to a slight de~ree, over of the later generations. t. tutional vigour of the Th h greater cons l d e roue If-fertilised plants, was prove . on crossed than of these. . namely by exposing . . n vanous ways ' ' :five occasions l 1 temperature or to a h'l ung to a ow them, w I e yo ' t or by growing them, dd h ge of tern per a ure, . . su en c an . bl ditions in competitiOn under very unfavoura e con . d ' 1 ts of other k1n s. wiwth ·f ull-grown p an h d tiveness of the crossed th respect to t e pro uc . l . . d 1 nts of the successive generatwns, and self-fert1hse P a t made on any my observations unfortunathely we~e ;~ime and partly 'f 1 partly from t e wan o ' uni orm pan: . intended to obser:ve more than from not havmg_ at fir~ of the results is here a single generation .. d f su~:a~;rtility of the crossed O'iven in a tabulate orm, e ~lants being taken as 100. . G t 'on o'·"' crossed and self-fertilised Plants F~rst enera ~ o S. t -five . in competition with one another.- IX y ~:~::;!s produced from flowers on five crosse~ffla~.!: fertilised by pollen from a distinct plant, a~~ fertil-ised capsules produced from flowers on five se . ds plants fertilised by their own pollen, contained see . 100 to 93 in the proportion of · · . · . · ·les on F'fty-six spontaneously self-fortihsed capsu 1 the above five crossed plants, and t wen ty- five spontlaf-- neously self-fertilised capsules on the abovet~ve s; 100 to 99 . fertilised plants, yielded seeds in the propor Ion o . CHAP. II. SUMMARY OF OBSERVATIONS. Combining the total number of capsules produced by these plants, and the average number of seeds in each, the above crossed and self-fertilised plants 57 yielded seeds in the proportion of . 100 to 64 Other plants of this first generation grown under unfavourable conditions and spontaneously self-ferti-lised, yielded seeds in the proportion .of . 100 to 45 Third Generation rf crossed and self-fertilised Plants. -Crossed capsules compared with self-fertilised cap-sules contained seeds in the ratio of 100 to 94 A.n equal number of crossed and self-fertilised plants, both spontaneously self-fertilised, produced capsules in the ratio of . 100 to 38 A.nd these capsules contained seeds in the ratio of . 100 to 94 Combining these data, the productiveness of the crossed to the self-fertilised plants, both spontane-ously self-fertilised, was as 100 to 35 Fourth Generation of crossed and self-fertilised Plants. -Capsules from flowers on the crossed plants fertilised by pollen from another plant, and capsules from flowers on the self-fertilised plants fertilised with their own pollen, contained seeds in the proportion of 100 to 94 Fifth Generation of crossed and self-jeTtilised Plants. -The crossed plants produced spontaneously a vast number more pods (not actually counted) than the self-fertilised, and these contained seeds in the pro-portion of 100 to 89 Ninth Generation of crossed and self-fertilised Plants. -Fourteen crossed plants, spontaneously self-fertilised, and fourteen self-fertilised plants spontaneously self-fertilised, yielded capsules (the average number of seeds per capsule not having been ascertained) in the proportion of . . • 100 to 26 Plants derived from a cross with a fresh Stock compared with intercrossed Plants.-The offspring of intercrossed plants of the ninth generation, crossed by a fresh stock, compared with plants of the same stock intercrossed during ten generations, both sets of plants left uncovered and naturally fertilised, produced capsules by weight as . 100 to 51 We see in this table that the crossed plants are |