(1

Conclusions on crossing Primroses & Cowslips 1865

After giving Gärtner's results & noting how he crossed them & that he knew nothing of dimorphism say I crossed homomorphically 6 3 long-styled & short-styled cowslips & J. Scott 8 of do by by pollen long-styled primrose & we I obtained 2 5 ([illeg]) pods, having on average 11 seed per pod. I crossed heteromorphically 6 pod of long-styled & short-styled & got 1 pod with got 81 48 seed — Mr Scott also crossed long-styled primrose, het. & hom. by cowslip pollens & got ave 3/8 pods from Hom. union alone with average of 11. seed.

Of reverse cross ie Primrose by pollen of Cowslip & Polyanthus I made a rather greater number of crosses, viz 15 long-styled primrose & 15 short-styled, & the result of the heteromorphic unions gave 6/15 pods with average of 37.1 seed & of Hom unions 4/15 with average of 13.0 seed. So common law of greater fertility of Het. than Hom. union holds in these hybrid union. —

I have said that I used pollen both of cowslip & Polyanthus, but the latter in aggregate of Het & Hom unions yielded 5/18 set & had average of 22.6 seed, whilst 5/12 set cowslip yielded 32.4.* (*I state this because Mr S. has drawn from my crosses which were communicated to him, results which I think are hardly founded considering how few the trials were) over.─

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Conclude with Bardfield — range different— no one can fail to perceive external differences. — I think Mr Doubleday detected distinction & he sent me plants

Though these crosses yield set very much fewer pods than natural unions & yield smaller average of seed, yet not so sterile as Gärtner; & but the number of seed does not give idea of sterility for the seed barely germinated, only in 1 case to be partly given.—

B

The sp. distinction of few, perhaps of no plant, has been so largely discussed as that of P. & C. Primula or cowslip not to mention their plain difference on flower & foliage, their geographical range is different, the cowslip extending &    their ascent up mountain is different, their odour stations are somewhat different— their time of flowering — the odour which they emit. But to come to less obli obvious difference— both require insect aid for perfect fertilisation; the C. being visited by humble bees, when larger insects are excluded, the C. is almost sterile not quite so the P. The P. when fully fertilized yields a greater average number of seed. But the most difference is that the P. is less dimorphic than the C. (give facts). Lastly the P. & C. are almost sterile when crossed (quote Gärtner give my own facts especially on Polyanthus see separate page of conclusions

Seeing these multiple differences, the onus probandi that these 2 forms are merely varieties clearly lies with those distinguished botanists who maintain this view, which is founded on the reported cases of variation & on gradation. (a) With respect to former, no better evidence then of dioecious plant had been cultivated —(give all references to facts merely in*). With respect to gradation, if oxlips be hybrids the case is explained— Hence having found Ø

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a group of oxlips, I removed them & next two year tried following experiments —

I crossed 10 long-styled & 10 short-styled flower reciprocally

(a) But I may first mention result of trying to cause cowslip to vary— see Experimental Book— I made these trial several years ago when I believe that one was Var of other—