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Show ORAl'. Il, . IPOMCEA PURPUREA. . . 32 in self-fertilised, the self-fertilised plants agaith the following crossed, and ~ro~l respects exactly as before, w were treated In a result:- (Third Generation.) TABLE III. 82 59 81 30 82 66 464•5 317'0 . . er than their antagonists : Again all the ~rosse.d p771~~~ ~:::::,hwhereas that of the self-height IS their average . hes or as 100 to 68 · f this third fertilised Id·s d52~~!~~; to 'the fertility of tdhe pl!:!s ~ere crossed I atten e the crosse P t' . Thirty flowers on f the same genera lOll, generatiOn. ther crossed plants o t . ed on an . h Hen from o duced con ain ' wit po t ty-six capsules thus pro the self-fertilised and the wen eds. whilst thirty flowers on flower produced average, 4·!? s~ 'th the pollen from the same d 'Thus the plants, fertihse WIles each containing 4. 43 see s. to that in twenty-three capsu 'a . the crossed capsules was d f the umber of see sIn g4 A hundre o average n ilised capsules as 100 to. . undred of the selfthe self-fert . hed 43.27 grains, whilst a h f these lighter crossed seeds weig 37 . 63 grains. Many o h fertilised seeds weighed o~ly damp sand germinated b~fore t 1 e self-fertilised see~s pl~ce t~he former germinated whllstpo~ i crossed. thus thuty-six o d seeds O'erminated. In o t. thirteen' of the 1a t te r or crodsusec ed spontoa neously und er ·the lnees ) the three crossed plants. pro t'fi . lly cross-fertilised capsu besides the twenty-six ar I Cia ontaining on an average ( enty-seven self-fertilised capsules_fc ·t"lised plants produced ~~~i seeds; whils.t the thr~:t s~~~r:: ~rtificially self-f~rtlllS~~ spontaneously (besldes t~e t:,lf-f!rtilised capsules, contam;ng eds capsules) only twenty-nine erefore the average number o se as an average 4·14 seeds. ;~eously self-fertilised ·capsules was in the two lots of spon a CHAP. II. CROSSED AND SELF-FERTILISED PLANTS. 33 100 to 94. Taking into consideration the number of capsules together with the average number of seeds, the crossed plants (spontaneously self-fertilised) produced seeds in comparison with the self-fertilised plants (spontaneously self-fertilised) in the proportion of 100 to 35. By whatever method the fertility of these plants is compared, the crossed are more fertile than the self-fertilised plants. I tried in several ways the comparative vigour and powers of growth of the crossed and self-fertilised plants of this third generation. Thus, four self-fertilised seeds which had just germinated were planted on one side of a pot, and. after an interval of forty-eight hours, four crossed seeds in the same state of germination were planted on the opposite side; and the pot was kept in the hothouse. I thought that the advantage thus given to the self-fertilised seedlings would have been so great that they would never have been beaten by the crossed ones. They were not beaten until all had grown to a height of 18 inches; and the degree to which they were :finally beaten i shown in the following table (No. IV.). We here see that the average height of the four crossed plants is 76 · 62, and of the four self-fertilisfld plants 65 · 87 inches, or as 100 to 86 ; therefore less than when both sides started fair. TABLE IV. (Third Generation, the se1f-fertilised Plants having had a start of forty·ei.ght hour,c;.) No. ofPot. Crossed Plants. Self-fertilised Plants. Inches. Inches. III. 1sa 73~ 77 ~ 53 73 61~ 77~ 75~ Total inches. 306·5 263·5 Crossed and self-fertilised seeds of the third generation were also sown out of doors late in the summer, and therefore under unfavourable conditions, and a single stick was given to each lot of plants to twine up. The two lots were sufficiently separate so as not to interfere with each other's growth, and the ground was clear of weeds. As soon as they were killed by the :first frost (and there was no difference ~n their hardiness), the two tallest crossed plants were found to be 24 .· 5 and 22 · 5 inches, D |