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Show 154 LATHYRUS ODORATUS. · CIIAP. v. 11 k n varieties occasionally gives birth to another, of the five we - now · t th' · whi.C h exhi.b i. ts aI I I· ts us ual characte.r s.. Owi·n g. oh IS cut nous f t d to the darker-coloured vaneties being t e mos pro-daucc t'.la vne these I. ncrease, to the exclusion of the other. s, as I was . 'a b th l t Mr Masters if there be no selectwn. Informe yt e a te . w. hat wo~ld be the effect of crossing two In order o ascer ain . h h van.e ti.e s, some fl owers on the Purple. swee. t-pea, whiC. d a·s a dark reddish-purple standard-petal with vwlet-co]ouie wmg- ~tals and keel, were castrated whilst very Y?ung, and '~ere p . . d 'th llen of the Painted Lady. This latter vanety fertilise WI po ' . t 1 ·t T . , has a pal e cl 1 erry-c Oloured ·s tand. ard ' with almos w u e ". mgs d k 1 On two occasions I raised from a flower thus crossed an ee . f b t tl . t , 1 t perfectly resembling both parent- orms; u 10 grea cr p anbs mbled the paternal variety. So perfect was the num er rese · · tl resem bl ance, tl at I should have suspected some mistake m ·1e 1 1 . . . label, had not the plants, which were at fir~t Identical m appcar- ance WI' th the f'a ther or Painted Lady, later Ill the sena so. n p. roduc.e d flowers blotched and streaked with dark purple. I his. IS. a~ m-teresting example of part.ial reversion in the sttme mdrndual plant as it grows older. The purple-flowered plants were thrown away, as they might possibly have been the prod~c~ of the accidental self-fertilisation of the mother-plant, owing to ~he castration not having been effectual. But the plants .. whwl~ resembled in the colour of their flowers the paternal vanety or P~inted Lady were preserved, and their seeds saved. Next summer many plants were raised from these . seeds, and they generally resembled their grandfather the Painted ~ady, ~ut most of them had their wing-petals streaked and stamecl Wlth dark pink; and a few had p~le purple wings wit~ the stanclar~ of a darker crimson than IS na.tural to the Pamted Lady, 8 that they formed a new sub-variety. Amongst these plants a single one appeared having ,purple flowers like th?se of th~ grandmother but with tho petals slightly streaked Witl~ a pale tint· this wa's thrown away. Seeds were agm·n sav d f1·o m thed foro~oing plants and the seedlings thus raised still _ resemb~e l the Painted Lady or great-grandfather; but they now va:Iec much the standar' d petal varying from pale to d ttr k rc d' m..a d few in' stances w.i th blotches of w hI' te ; and the wing -petals. vane 1 .t from nearly white to purple, the keel being in all nearly w 11 . 0 · d As no variability of this kind can be detected in plants raise fro.m seeds the parents of which have grown (1 u n.·n oo· m any tshu e- cessive gen' erations 1. n close proxi· mi· ty, we may I·n fe r that ey CHAP. v. LATHYRUS ODORATUS. 155 cannot have intercrossed. What does occasionally occur is that in a row of plants l'aisocl from seeds of one variety, another variety true of its kind appears; for instance, in a long row of Scarlets (the seeds of which had Leon carefully gathered from I Scarlets for the sake of this experiment) two Purples and one Painted Lady appeared. Seeds fron1 these throe aberrant plants were saved and sown in separate beds. Tho seedlings from both the Purples were chiefly Purples, but with some Painted Ladies and some Scarlets. The Roedlings from tho aberrant Painted Lady were chiefly Painted Ladies with some Scarlets. Each variety, whatever its parentage may have been, retained all its characters perfect, and there was no streaking or blotching of the colours, as in tho foregoing plants of eroswd origin. Another v~riety, however, is often Rold, which is striped and blotched With dark purple; and this is probably of crossed origin, for I found, as well as l\fr. Masters~ that it did not transmit its characters at all truly. From the evidence now given, we may conclude that the varieties of the sweet-pea rarely or never intercross in this country; and this is a highly remarkable fact, considering, firstly, the general structure of the flowers; secondly, the large quantity of poll~n produced, far more than is requisite for self-fertilisation; and th1rdly, the occasional visits of insects. That insects should someti~~s fail to cross-fertilise the flowers is intelligible~ for I have thr1ce seen humble- bee~ of two kinds as well as hive-bees sucking the nectar, and they did not depr~ss the keel-petals s; ~s to ~xpose the anthers and stigma; they were therefore quite meffiCient f~r fe~tilising the flowers. One of these bees, namely, Bom~us lap~da?·tus, stood on one side at the base of the standard and mserted its proboscis beneath the single separate stamen as I afterwards ascertained by opening the flower and findino· this stam en pn·s ed up. Bees are forced to act in this mannero from the slit in the stamina! tube being closely covered by the broad membranous margin of the single stamen and from the tube ~ot being perforated by nectar-passages. 'On the e>ther hand, In th? three British species of Lathyrus which I have examined, and m the al!i~d genus Vicia, two nectar-passages are present. Therefore Br1t1sh bees might well be puzzled how to act in the case of the sweet-pea. I may add that tho stamina! tube of another exotic species, Lathyrns g,·arul,;jlorw:, is not perfo:~ te_d by nectar-passage~, and this species has rarely set any P 8 m my gardenJ unless the wing-petals were moved up and |