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Show CHAP. III. MIMUL US LUTE US. 80 d . ther for cross·i ng or self-how far it was at first use hei eneration most of the fertilisation. In the fi~ i; the sixth and ~ll the If-fertilised plants, an . le plant consisted of se . every smg · t succeeding generatlons d bt was partly due to I s this variety; and th~s no sel~~ertility. On the other gr.e at and increasdi nfgr om amongs t the crossed pbl abnlt s hand, it disappeare . . and this was pro a y . the later generations' . g of the Reveral m . d intercrossm lf due to the continue f this variety, the se - plants. From . the tallnes~h~ crossed plants in height fertilised plants ex_ceedef~om the fifth to the s~venth . all the generations ld have done so In thEl m d doubt won ff inclusive; an_ no d th been grown in compe I IOn later generatwns, ha :y fifth generation the crossed with one an~ther .. ~n :o ethe self-fertilised, as 100 to plants were 1~ helg ~00 to 147; and in th~ sevent~ 126; in the sixth, as 137 This excess of height n:al generation, as 100 to t this variety naturally gr~wmg be attributed not only o b t to its possessing a h ther plants, u .cr f taller than t ~ o. that it did not suuer rom peculiar const1tuti_o~, ~0 . continued self-fertlhsatwn. trikin ly analogous case ~o This variety presents a s H g hich appeared 111 that of the plant ca 11 ed the erto' , nw of Ipomcoa. If' ·r d o-enera 10 · the sixth self-ferti Ise o . h d been as greatly 111 the seeds pro d uce d by dH be roth e ao ther plants, as was the excess of tho~e produce d ~f all the seeds had been case with Mimulus, an . f Hero would have . ngled together, the_ offspnnlg _o of tho ordinary ml the entue exc uslon . d from increased to lf f tilised generatwns, an h plants in the later se - er ld have exceeded t e naturally gro':ing _tall~: :aoc~ succeeding generation. crossed plants In heigh~ I. nts of the sixth gene· S f the self-fertilised pla . the eighth ratioonm ew eor e intercrosse d ' as ,vere some In CHAP. III. DIGITALIS PURPUREA. 1 generation; and the seedlings from these crosses were grown in co1npetition with self-fertilised plants of the two corresponding generations. In the :first trial the intercrossed plants were less fertile than the selffertilised, and less tall in the ratio of 100 to 110. In the second trial, the intercrossed plants were 1nore fertile than the self-fertilised in the ratio of 100 to 73, and taller in the ratio of 100 to 92. N otwithstanding that the self-fertilised plants in the second trial were the .Product of two additional generations of self-fertilisation, I cannot understand this discordance in the results of the two analogous expOriments. The most important of all the experiments on Mimulus arc those in which flowers on plants of the eighth self-fertilised generation were again self-fertilised; other flowers on distinct plants of the same lot were intercrossed ; and others were crossed with a new stock of plants fron1 Chelsea. Thv Chelsea-crossed seedlings were to the intercrossed in height as 100 to 56, and in fertility as 100 to 4; and they were to the self-fertilised plants, in height as 100 to 52, and in fertility as 100 to 3. These Chelsea-crossed plants were also much more hardy than the plants of the other two lots; so that altogether the gain from the cross with a fresh stock was wonderfully great. Lastly, seedlings raised from a cross between flowers on the same plant were not superior to those fro1n flowers fertilised with their own pollen; but this result cannot be absolutely trusted, owing to some previous observations, which, however, were made under very nnfa voura ble circumstances. DIGITALIS PURPURE.A. The flowers of tho common Foxglove arc protorandrous; that is, the pollen is mature and mostly shed before the stigma of the same fiower is ready for fertilisation. This is effected hy G |