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Show 164 SAROTHAMNUS SCOPARIUS. CUAP. v. · h h 1 O'ated curved pistil spring forth with violence. w1th t c muc e onb . ' · · .. f' . · .. rrhe flattened, spoon-like extremity of :he pbtil rcs~s Ol a ti~e on t h e b ac k of tll e l)ee ' and leca. ves on It the •l oad of pollen w• ith• 1 · 1 ·t · 1-"rged As soon as the bee fl.Jcs away, the p11:>hl W llC 1 I IS C lw · . . . . I· ns t an tly cur· 1 R round , so that the stigm. atic• surface IS now up-turne d ·a n d oc cupi·es a IJosition ' in wh1.e h_ .I t would be rubbed agai·n s t the a bdomen of another bee VISiting the same flo.w er. Th h n the pistil first escapes from the keel, the stJgnm is ~~b:e; against the back of the bee, dust d with pollen from the longer stamens, either of the same or another flower; d ft wards ao·ainst the lower surface of the boo dusted an a er o . l . ft l J · th llen from the shorter stamens, w hlC 1 Is o en s 1CCL a WI po * B 1 · day or two before that from the longer stamc~s. 't bly t 1~ mechanism cross-fertilisation is rendered almost _In?vi Ja c, an_ we shall immediately see that , pollen from a distinct plant m n1ore effective than that fro1n the same flower. I need only aJd that, according to H. Muller, the flowers d? not. scc~·ctc nectar, and he thinks that bees insert their proboscides only 1n the hope of finding nectar; but they act in this manner so f~·cquently and for so long a time that I cannot avoid the belief that they obtain something palatable within the flowers. If the visit.s of bees are prevented, and if the flowers arc not dashed by the wind against any object, the keel never opens, so that the stamens and pistil remain c~closed: rlants thus protected yield very few pod in companHon with 1~1oso l)roducecl by neighbouring uncovered bushes, and sometn~1cs none at all. I fertilised a few flowers on a plant growmg almost in a state of nature with pollen from another plant close alongside, and the four crossed cap ules contained on an average 9 · 2 seeds. This large number no doubt was duo to the bush being covered up, and thus not cxhaus~e~ _by producing many pods; for fifty pods gathered from an adjommg Jllant, the flowers of which had been fertili. ·od by the l>ecs, contained an average of only 7 ·14 sec l s. Ninety-three pods spontaneously self-fertitisccl on a large lm::;h which ltad ~een covered uv, lmt had been rnuch agitH.tocl by the wind, cont_mnod an average of 2 · 93 seeds. Ten of tho iinc::;t of these mnety- * Thc·sc ub:,ervati(lliS have Leon quuic(l iu a11 aLl~reviutt <1 furm by tho He\·, G. Henslow, in the 'J ournn1 of Linn. ~oc. But.' yol. ix. 18GG, p. 358. ~1. l\Ji.il1c~· ] I~~ :,inc puhli~li ed a full anu ~xcc. le11t account of the flo"or 111 l.us 'Befruchtung,' &c. p. ~4.0. CHAP. v. SAROTHAMNUS SCOPARIUS. 165 three capsules yielded an average of 4 · 30 seeds, that is loss than half the_average number in the four artificially cros.·ed cnpsules. T~e ratw of 7 ·14 to 2 · 93, or as 100 to 41, is probably the fa1rest for the num bcr of seeds per pod, yielded by naturallycrossed and spontaneously self-fertilised flowers. The cro~sccl see~s. compared with an c~ua~ number of the spontaneously selffertilised se~ds were hcavwr, 1n the ratio of 100 to 88. vVe thus see that besides the mechanical adaptations for cross-fertilisation, t~e. :flowers are much more productive with pollen from a d1st1nct plant than with their own pollen. Eight pairs of the above crossed and self-fertilised seeds after they ~ad. germinated on S3,nd, were planted (1867) 0~ the opposite _SJdcs of two large pots. When several of the seedlings were an rnch and a half in height, there was no marked difference between the two lots. But even at this early age tho leaves of the self-fertilised seedlings were smaller and of not so bdght a green as those of the crossed ·seedlings. The pots were kept in the greenhouse, and as the plants on the following spring (1868) lo?k~d un~ealthy and had grown but little, they were plunged, still In theu pots, into the open ground. The plants all suffered· much from the sudden change, especially tho self-fertilised and t~o of the latter died. The remainder were measured, ~nd I give the ~easurements in the following table, because I have not seen In any other species so great a difference between the crossed and self-fertilised seedlings at so early an age. TABLE LVIII. Farotllamnus scoparius (very young plunts ). No. ofPot. Cros eel Plants. I Self-fertilised Plants. Inches. Inchrs. I. 44g 24 6 1 4 2 B 1 I II. 2 1~ 2 H4 1 04g 04g --- - -- - Total in inches. 17•5 8•0 The six crossed plants here average 2 · 91, and the six self- |