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Show 338 · SELF-STERILE PLANTS. CHAP. IX. attractecl b y tl1 c 0 dour ' had on some onef occafs lOn found an en t .ranc.e, ancl ha" d intercrossed a ew o the flowers. · 1 f' f h I n th e spn· ng.o f 1869 four plants ra1sec rom res d Isee s were ca ·eftllly I)rotectecl under separate .n ets; ancl now the result was widely different to what 1t was before. Three of these protected pla1~ts bocLune actually loaded with capsules, especiall~ d1~nng the early ~art o f tl1 e sum mer ,. 'a nd this fact 1nd1cates th. at tmnp.e ra-ture produces some effect, but the oxpern~ent given in the following paragraph shows t~1at the Innate constitution of the plant is a far n1ore unportant oleinent. The fourth plant produced only a few capsules, Ina~y of them of small size ; yet it was far n1ore solf-fe1:tile than any of the seven plants trie~ during the prevw~s year. The flowers on four small b~anches of this seini-self-sterile plant were smeared. w1th pollen from one of. the other plants, and they all produced fine capsules. . . As I was much surprised at the cl1fferonce In. the results of the trials made during the two prevwus years, six fresh plants were protected by separate nets in the year 1870. Two of those proYecl ~hnost completely self-sterile, for on carefully search:n? th~m ~ found only three small capsu~es, eac~ conta1n1ng .eit~e~ one or two seeds of small size, wh1ch, however, gernlinated. A few flowers on both tl~ese plants were reciprocally fertilised with each other's pol~en: an~: a few with pollen fro1n one of the following s~lf fertile plants, and all these flowers p~oduced. ~n~ capsules. The four other plants whilst stillrenla.Inmg Protected beneath the nets presented a wonderful co· ntrast (though one of them 1· n a son1 ewhat less degree than the others), for thoy becmne actually covered with spontaneously se lf- f er t1.l .1 se d capsules ' as CHAP. IX. SELF-STERILE PLANTS. 339 numerous as, or very nearly so, and as fine as those on the unprotected plants growing near. The above three spontaneously self-fertilised cap-. sule.s produced by ~he two ahnost completely self~ tenle plants, .cont~1ned altogether five seeds; and fr01n these_ I raised 1n the following year (1871) five plants, which were _kep~ under separate nets. They g1:ew to an extra?rchnanly large size, and on Augu~t 29t~ were e.xanuned. A.t first sight they appeared ~ntuel~ destitute of capsules ; but on carefully searchv 1ng their many branches, two or three capsules were · found on three of the plants, half-a-dozen on the fourth, and about eighteen on the fifth plant. But all these capsules were small, s01ne being empty ; the greater number contained only a single seed, and very rarely more than one. .r\_fter this examination the nets were taken off, and the bees i1nn1ediately carried pollen from one of these almost self-sterile plants to the other, for no other plants grew near. After a few weeks the ends of the branches on all five plants became covered with capsules, presenting a curim.lR contrast with the lower and naked parts of the same long branches. ~rhese five plants therefore inherited almost exactly the same sexual constitution as their parents ; and without doubt a self-sterile race of Mignonette could have been easily established. Reseda Z.utea.-Plan ts of this species were raised ~ron1 seeds gathered from a group ·of wild plants growIng at no great distance from n1y garden. After cast~ally observing that so1ne of these plants were selfstenle, two plants taken by hazard were protected under separate rtets. One of these soon becaJne covered with spontaneously self-fertili~ed capsules, as numerous as those on the surrounding unprotected plants; so that it was evidently quite self-fertile. z 2 |