B. Seed-coats and Shapes. 1. Seed-coats, 148. 2. Seed-shapes: (_a_) Rimpau’s cases, 150. (_b_) Tschermak’s cases, 152. 3. Other phenomena, especially regarding seed-shapes, in the case of “grey” peas. Modern evidence, 153. C. Evidence of Knight and Laxton, 158. D. Miscellaneous cases in other plants and animals: 1. Stocks (_Matthiola_). Hoariness, 169. Flower-colour, 170. 2. _Datura_, 172. 3. Colours of Rats and Mice, 173. V. Professor Weldon’s quotations from Laxton, 178. Illustration from _Primula sinensis_, 182. VI. The Argument built on exceptions, 183. Ancestry and Dominance, 185. Ancestry and purity of germ-cells, 193. The value of the appeal to Ancestry, 197. VII. The question of absolute purity of germ-cells, 201. Conclusion, 208. ERRATA. p. 22, par. 3, line 2, for “falls” read “fall.” p. 63, line 12, for “_AabbC_” read “_AaBbc_.” p. 66, in heading, for “OF HYBRIDS” read “OF THE HYBRIDS.” _Note to_ p. 125. None of the yellow seeds produced by _Laxton’s Alpha_ germinated, though almost all the green seeds sown gave healthy plants. The same was found in the case of _Express_, another variety which bore some yellow seeds. In the case of _Blue Peter_, on the contrary, the yellow seeds have grown as well as the green ones. Few however were _wholly_ yellow. Of nine yellow seeds produced by crossing green varieties together (p. 131), six did not germinate, and three which did gave weak and very backward plants. Taken together, this evidence makes it scarcely doubtful that the yellow colour in these cases was pathological, and almost certainly due to exposure after ripening. THE PROBLEMS OF HEREDITY AND THEIR SOLUTION[3]. [3] The first half of this paper is reprinted with additions and modifications from the _Journal of the Royal Horticultural Society_, 1900, vol. XXV., parts 1 and 2. Written almost immediately after the rediscovery of Mendel, it will be seen to be already in some measure out of date, but it may thus serve to show the relation of the new conceptions to the old. An exact determination of the laws of heredity will probably work more change in man’s outlook on the world, and in his power over nature, than any other advance in natural knowledge that can be clearly foreseen. There is no doubt whatever that these laws can be determined. In comparison with the labour that has been needed for other great discoveries we may even expect that the necessary effort will be small. It is rather remarkable that while in other branches of physiology such great progress has of late been made, our knowledge of the phenomena of heredity has increased but little; though that these phenomena constitute the basis of all evolutionary science and the very central problem of natural history is admitted by all. Nor is this due to the special difficulty of such inquiries so much as to general neglect of the subject.