OCR Text |
Show CHAP. Ill. MIMUL US LUTE US. 64 . hare irritable and close , . . a the lips of whlC ollen is enclosed the two-hpped stig:~ pollen-grains. If ~0 p Mr. Kitchener like n, forcep~ onthese open again after a I:.~~ements, namely, between the lips, . d * the use of these If a bee with . · sly explaine f th flower. has Ingeni;~he self-fertilisation o ~ ·t touches the stigma, to preven its back enters a flower ;ee retires dusted with no pollen. on closes, and when th~ of the same flower. which quickly 1 ve none on the stigma lenty of pollen is 11 it can ea th r flower, P po en, on as it enters an! o eth s cross-fertilised. Never- But as so t' Ina which will be u fertilise themselves left on t~e i~::cts 'are excluded, the:~~~: I did not ascertain thel~ss, I d produce plenty of see ' increasing in length ~~~~~;'::is is effected by th:e:1~~e~~wn of the pistil.. The with advancing age, or by_.th:nts on the present specws, hes/n chief interest in ~y expe~:~rth self-fertilised gcnemtw~ ore: earance Ill the . 1 coloured flowers, an g the. ~ppwhich bore large peculiar y· . ties. it likewise became ;:~cg~eater height than the o!~~ v:~: va;iety resembles the m.ore hI.g hly Hse lf-ferwtihleic, h soa ppe"a re d I. n the sixth self-fertilised l t named ero, Pg eanne rati.O n of I po mcea. f the plants rai.s ed from the p. urchastehde Some flowers on one~ . wn ollen; and others on seeds were fertilised wdith.:J:epi~l~en f~om a distinct plant. lT~e same Plant were crosse WI duced were placec m 1 s thus pro h · , see d s from twelve capfs u ec ompan.s on ., and those from t e SIX te watch-glasses or hardly more numerous separa eared to the eye t hen the crossed capsules app. If-fertilised capsules. Bu w t d than those from the SIX se the crossed capsules amoun e seeds were weighed,. those fromfrom the self-fertilised ca~sules to l· 02 grain, ":hi:sto ~oa~e the former were either heavier or were only . 81 gram~ ~he latter, in the ratio ~f 100 to 7.:Raving more numerous tha if the F·ir-st (Teneratwn. Crossed and self-fertilised Pla?d'lts v d self-f~rtilised seed on damp ascertained, b y 1e av ing ·cnraotsesde siamnu ltaneously, bol1l 1n ·n d sh were !low sand, that they germ: . f a broad and rather s a thickly sown on opposite sides o . s which came up at the , pan ; so tha' t the two sets of tshe edlimnge 'u nf n. v ourable conditions.f . were subjected to e sa . ecies was one o ~::~ !:e~ bad method of_trea~m;n\~~~!h:~:~rosscd seedlings the first on which I experimen e . * 'A Year's Botany,' 1874, P· 118. CHAP. Ill. CROSSED AND SELF-FERTILISED PLANTS. 65 were on au average half an inch high, the self-fertilised ones were only a quarter of an inch high. When grown to their full height under the above unfavourable conditions, the four tallest crossed plants averaged 7 · 62, and the four tallest self-fertilised 5 · 87 inches in height; or as 100 to 77. Ten :flowers on the crossed plants were fully expanded before one on the self-fertilised plants. A few of these plants of both lots were transplanted into a large pot with plenty of good earth, and the self-fertilised plants, not now being subjected to severe competition, grew during the following year as tall as the crossed plants; but from a case which follows it is doubtful whether they would have long continued equal. Some :flowers on the crossed plants were crossed with pollen from another plant, and the capsuleH thus produced contained arather greater weight of seed than those on the self-fertilised plants again self-fertili~ed. Crossed and self-fertilised Plants o/ the Second Generation.-Seeds from the foregoing plants, fertilised in the manner just stated, were sown on the opposite sides of a small pot (I.) and came up crowded. The four tallest crossed seedlings, at the time of flowering, averaged 8 inches in height, whilst the four tallest self-fertilised plants averaged only 4 inches. Crossed seeds were sown by themselves in a second small pot, and selffertilised seeds were sown by themselves in a third small pot; so that there was no competition whatever between these two lots. Nevertheless the crossed plants grew from 1 to 2 inches higher on an average than the self-fertilised. Both lots looked equally vigorous, but the crossed plants :flowered earlier and more profusely than the self-fertilised. In Pot I., in which the two lots competed with each other, the crossed plants :flowered first and produced a large number of capsules, whilst the self-fertilised produced only nineteen. The contents of twelve capsules from the crossed :flowers on the crossed plants, and of twelve capsules from self-fertilised :flowers on the self-fertilised plants, were placed in separate watch-glasses for comparison; and the crossed seeds seemed more numerous by half than the self-fertilised. The plants on both sides of Pot I., afte1· they had seeded, were cut down and transplanted into a large pot with plenty of good earth, and on the following spring, when they had grown to a height of between 5 and 6 inches, the two lots were equal, as occurred in a similar experiment in the Jast generation. But after some weeks the crossed plants exceeded the self- F |