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Show 206 NICOTIANA TABACUM. CHAP. VI . that the plants raised from the crossed seeds were inferior in height to those from the self-fertilised seeds; but only when not greatly crowded. When crowded and thus subjected to very severe competition, the crossed and self-fertilised plants were nearly equal in height. Crossed and self-jeTtiUsed Plants of the Second Generation.Twelve flowers on ·the crossed plants of the last generation growing in the four large pots just mentioned, were crossed with pollen from a crossed plant growing in one of the other pots; and twelve flowers on the self-fertilised plants were fertilised with their own pollen. All these flowers of both Jots produced fine capsules. Ten of the crossed capsules contained by weight 38 · 92 grains of seeds, and ten of the self-fertilised capsules 37·74 grains; or as 100 to 97. Some of these seeds in an equal state of germination were planted in pairs on the opposite sides of five large pots. A good many of the crossed seeds germinated before the self-fertilised, and were of course rejected. The plants thus raised were measured when several of them were in full flower. TABLE LXXXV. Nicotiana tabacum ( Second Generation). No. of Pot. Crossed Plants. Self-fertilised Plants. Inches. Inches. I. 14a 27 ~ 78 ~ 86 l! 9 56 II. 603 16S 44H 7 10 50 ~ III. 57k 87 (A) 1g 81 g (u) IV. 6H 19 31 43g 6 9~ 4 v. 99a 94 l! 29§ 3 Total in inches. 511·63 413•75 CHAP. VI. CROSSED AND SELF-FERTILISED PLANTS. 207 The thirteen crossed plants here . average 39·35, and the thirteen self-fertilised plants 31· 82 inches in height; or as 100 to ~1. But it would be a very much fairer plan to exclude all the starved plants of only 10 inches and under in height; and in this case the nine remaining crossed plants average 53· 84, and the seven remaining self-fertilised plants 51· 78 inches in height, or as 100 to 96; and this difference is so srriall that the crossed and self-fertilised plants may be considered as of equal heights. In addition to these plants, three crossed plants were planted separately in three large pots, and three self-fertilised plants in three other large pots, so that they were not exposed to any competition; and now the self-fertilised plants exceeded the crossed in height by a little, for the three crossed averaged 55· 91, and the three self-fertilised 59 ·16 inches; or as 100 to 106. Crossed and self-fertilised Plants of the Third Generation.-As I wished to ascertain, firstly, whether those self-fertilised plants of the last generation, which greatly exceeded in height their crossed opponents, would transmit the same tendency to their offspring, and secondly, whether they possessed the same sexual constitution, I selected for experiment the two self-fertilised plants marked A and B in Pot III. in Table LXXXV., as these two TABLE LXXXVI. Nicotiana tabacum (Third Generation). Seedlings from the Self-f~:rtilised Plant A in Pot IlL, Table LXXXV., of the last or Second Generation. From Self-fertilised From Self-fertilised Plant again self-ferti- No. of Pot. Plant, crossPd by a li sed, forming the Crossed Plant. Third Self-fertilised Generation. Inches. Inches. I. 100g 98 91 79 II. llOg 59 ! 100 ~ 66 g III. 104 79 g ·- IV. 84! 110 ~ 7 6~ 64A Total in inches. 666•75 557• 25 |